CA1271150A - Microbial enhancement of polymer viscosity - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A method for enhancing the viscosity of a polymer solution with certain microorganisms. The intrinsic viscosity of a solution of preformed polymers is increased or stabilized when that solution is subjected to microbial action. The microorganisms employed are incapable of a de novo synthesis of the subject polymers, but are nevertheless capable of increas-ing the solution vicosity. The vicosity is enhanced relative to a solution which does not contain the microorganism.

Description

~71~SO (5792) MICROBIAL ENHANCEMENT OF POLYMER VISCOSITY

BACKGROUND OF THE INVENTION
Field of the Invention This invention relates to the action of microor~anisms on polymers contained in solution. More particularly, the invention concerns a process for increasing the viscosity of a polymer solution through the use of microorganisms.
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Discussion of the Art For the purposes of this patent, all polymers can be divided into two classes: biopolymers and synthetic polymers.
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~` Biopolymers are polymers produced at least in part by the . .
~ ~ action of biological processes, while synthetic polymers are :
; produced by chemical processes.
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Biopolymers can be~obtained from a variety of natural ;~ plant sources, includin~ tree exudates, seed e~tracts, seaweed, ~starches, and cellulose derivatives. Some biopolymees, such as :: ~ :
~ certain polysaccharides can be produced by microorganisms.
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A well-known example of a microbial biopolymer is xanthan gum, which is an anionic heteropolysaccharide made exocellul~rly from carbohydrate substances by organisms of the ; genus Xanthomonas, such as X. campestris and X. be~oniae.
~; ; Xanthan and several other microbial biopolymers, such as the fung~l product scleroglucan sold by the Pillsbury Company under ~, , the trade name "Polytran" and a polysaccharide ob~ained from the~soil bacteria Erwin_ marketed under the trade name , ';~`~ 1.
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~73~15~3 (5792) "Zanflo", are available in commercial quantities for applications including inks and coatings, cosmetics, ceramics, paint thickeners, drilling muds, pharmaceuticals, and foods.
Some microbial biopolymers have the ability to function as surfactants, such as surfactin produced by Bacillus_subtilis.
These surfactants are useful as flocculating agents, emulsi~iers, demulsifiers, detergents, adhesives, and enhanced oi1 recovery fluids.
A microbial ~iopolymer is generally obtained by either fermentative or enzymatic synthesis. In fermentation, a microorganism that is ~enetically capable of building a specific polymer is placed in a medium with the necessary nutrients and substrate. The polysaccharide is recovered fro~
this medium. In enzymatic $ynthesis, microbial cells are withdrawn from a cell culture, leavin~ a culture fluid containing the extracellular enzyme. The enzyme is then contacted with the substrate to produce the polysaccharide.
Further information on polysaccharides and their manufacture can be found in "Microbial Polysaccharides," Kirk-Othmer Encyclopedia of Chemical Technolo~, 3rd Ed., Vol. 15 at pages 439-5~.
Synthetic polymers are prepared by the combination of one or more types of monomeric materials under conditions ~ .
suitable to polymerization. They are generally less complex than biopolymers, usually consisting of an orderly progression of simple monomer units.
80th biopolymers and synthetic polymers can be added ~ to water or other solvents in order to form solutions having ; beneficial characteristics, such as increased solution viscosity. The viscosities of these solutions can vary ~reatly depending the amount of the polymer in solution, the molecular weight and conformation of the polymer, temperature, the * trademark :: 2 .~ .

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(5792) presence of salts (especially multivalent salts such as magnesium and calcium), and other factors.
The continued stability of polymer solutions under conditions of severe temperature, salinities, pressures, shear forces, and the presence of oxygen and chemicals is a major concern for some applications. Some microorganisms, whether naturally present in the solution environmen~ or introduced by contamination, are also capable of degrading polymeric substances and thereby decreasing the solution viscosity. For example, many microorganisms secrete enzymes (cellulase, amylase) that can hydrolyze polysaccharides into monosaccharides that can be used in the organism's metabolism.
Synth~tic polymers can also lose viscosity under microbial attack.
For the reasons given above, one of the objects of current research i5 to produce stable polymer solutions. The solution must be stable to the chemical, thermal, and biological conditions encountered in various industrial processes. Of parti ular interest is the search for a polymer solution for use in enhanced oil recovery that will maintain its stability during pretreatment steps, injection, and throughout the reservoir, For economic reasons, another object is to obtain the maximum viscosity for the least cost, i.e., the most viscosity from the least amount of polymer in the solution.

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(5792) SUMMARY OF THE INVENTION
The invention concerns a method for enhancing the viscosity of a solution of preformed polymers by combining that solution with a microorganism ineapable of de novo synthesis of said polymers but capable of increasing the viscosi~y of said polymer solution, and maintaining that solution at conditions favorable for microbial growth. The viscosity of this solution is increased or stabilized relative to a solution which does not contain the microorganism.
The microorganisms used to increase the viscosity of a chosen preformed polymer can be selected by using a microbial screening process characterized by (a) preparing a growing culture of the microorganism;
(b) preparing an aqueous solution of the preformed . polymer and adding nutrient~ and minerals required for microbial growth;
~c) separating that solution into two portions: a test and a control;
d) inoculating the test solution with the culture oE
: the microorganism and incubating the mixture; and (e) measuring~the viscosities of both test and . : , , : control solution~ after incubation to determine if the test solutlon is relatively more viscous than the control.

DETAILED DESCRIPTION
It has now been discovered that certain microorganisms are capable of increasing ~he viscosi~y of a polymer solution :
~ : even when that microorganism is itself genetically incapable of : ~ :
de novo synthesis of the polymer. The term "de novo" is used in this patent to exclude those known techniques where a 4.
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nicroorganism contructs polymeric material (such as polysac-charides) from monomers, and thereby increases the viscosity of a solution. As this invention is defined, the microorganism cannot build the chosen polymer from ~ono~ers. This method is therefore most appropriate for preformed polymers (i.e., polymers which have previously been produced by either chemical or microbial syntheses). For example, a particular micro-or~anism can be ~enetically incapable of manufacturing a polysaccharide, but is capable o~ alteringithat a solution of that polysaccharide to effectuate an increase in its viscosity.
While not`intending to be bound by a particular theory, it is believed that the microor~anism acts to increase the avera~e molecular weight oE the polymers in solution, possibly throu~h ehe action of one,or more enzymes. A detailed description of suitable polymers, microorganisms, viscosity chan~es, and the process is given below.

Polvmers _ The poly~ers useful in this invention include any biopolymers and synthetic polymers that are compatible with water. Preferred polymers are not only compatible with water, but are readily solu~le in water because they will thus be easily accessible to the microor~anism.s and any accompanying . .
extracellular enzymes in an aqueous media. However, even partially-soluble or water-insoluble polymers are-contemplated ~ to be within the scope o~ this invention, provided t~at an ; interfaee exists between the polymer and the microorganism or ~` enzymes.~
In the preferred practice of the invention, the polymer can be chosen from those known to be effective for a particular end use. For example, a polyacrylamide can be , * For the purposes of t~i's invention, a "solut~on" of polymer means, in a~dition to dissolved polymer, any ~ater weta6le polymer surface such as polymer suspensions, colloidal dispersions, polymeric gels or emulsions, and weta~le polymer;~c solids.

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(5792) chosen if the desired use is water treatment, enhanced oil recovery, mineral processing, or pulp and paper processing.
Extensive information has been published on applications for polymer solutions. Lon~-chain water-soluble polymeric materials are extensively used as flocculation aids for solid-liquid separations. The use of aminated starches, polyamines, and polyacrylamides in industrial water treatment is summarized in "Water (Industrial)", Kirk-Othmer Encylopedia of Chemical Technolo~, 2d Ed., Vol.22. Other polymer flocculants are used in processes such as water clarification, sewage treatment, metal finishing, paper production, sugar refinin~, mineral extraction, and food processing as discussed in "Flocculating Agents", Kirk-Othmer Encylopedia of Chemical TechnoloRy, 3d Ed., Vol.10.
` .Enhanced oil recovery (EOR) usually requires the injection of an aqueou~ fluid, s~ch as water or brine, to push ~;the oil ahead of it through the formation to a production well. A polymer is often added to at least a portion of the injected Çluid in order to form a slug having increased viscosity. The polymer-thickened fluid moves in an even front and minimizes the by-passing and f in~ering that mi~ht otherwise occur during conventional waterflooding.
; Polymers considered to be useful for enhanced oil recovery (EOR) include guar ~um, hydroxypropyl guar, sodium carboxymethyl cellulose,hydr~ethyl cellulose, carboxymethyl .~
hydroxyethyl cellulose, xanthan gum, glucan, locust bean ~u~, ~olyacrylamide, hydrolyzed polyacrylamide, poly(acrylic :: ~
~ acid) and salts~poly(2~acrylam~do-2-methyl propone sulfuric acid)(2 ; salt) ~AMPS), poly(acrylic acid-co-acrylate ester), poly (vinyl : :: pyrrolidone), cellulose sulfate esters, poly (ethylene oxide), poly (vinyl alcoholj, polyamine, poly(vinyl acetate-co-maleic anhydride3, and poly (styrene sulfonic acid) and salts.

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(5792) Preferred among these are hydroxyet~yl cellulose, carboxymethyl hydroxyethyl cellulose, xanthan gum, and hydrolyzed polyacrylamide.
The concentration of the polymer solution used in EOR
is generally determined by the permeability of the rock and the viscosity of the oil in the reservoir. For economic reasons, the concentration is kept to the minimal effective levels, which are typically between 20 ppm and 3000 ppm, more typically 50 to 1000 ppm and most typically 200 to 600 ppm. High temperatures, shear stresses, high salinity, extreme pH values are other reservoir conditions which must be considered in choosing an ef~ective polymer.
Polymers are otherwise used in oil fields in drilling, cementing, fracturing, acidizing, controlling water production, . preventing sand production, clay stabili~ation, lost circulationf and the like. Guar, guar derivatives, ; cellulosics, xanthans, locust bean gums, starches, and ; synthetic polymers such as polyacrylamide are commonly used, as more fully described in Chatterji, J. and Borchardt, J.K., "Applicstions of Water-Soluble Polymers in the Oil Field", J.
: Pet. Tech. 2042-2056, (Nov. 1981).
Preferred polymers for EOR mobility control agents ~:~ will have all or most of the following character;stics :
1~ Ready solubility in water with a high positive :~ : affect on solution viscosity;
: 2. Tolerance of dissolved salts (brine) in the , aqueous solvent;
3. High molecular weight for maximum viscosity effect;
4. Devoid of excessive brsnching or gels that might cause injection problems;

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(5792) S. Stability under thermal, biological, and shear s~resses in the reservoir environment and injection process;
6. Potentially inexpensive in large volume production or having a high volume natural source.

M_asurement_of Viscosit~
The viscosity of a water-soluble polymer in solution is a function of many factors, chiefly molecular weight and electrolytic character. The greater the molecular weight of the polymer, the greater is the viscosity. Char~ed polymers also tend to lose viscosity in highly saline water due to neutralization of the charges by the ions in solution.
The classic definition of viscosity for Newtonian fluids will be employed in this patent, where viscosity equals shear stress over the rate of shear. Shear stress is further defined as the force per unit area required to produce the ~; shearing act;on. The rate of shear is a measured value.
A suitable way to measure viscosity is to employ a ;~vi~scometer such as one manufactured by Brookfield Engineering Laboratories, Inc., of Stoughton, Massachusetts. The ~, ~roo~field Viscometer measures viscosity by measuring the force; required to rotate a spindle in a fluid. Because practically all fluids become thinner~ as temperature increases and thicker as they cool, the temperature of the fluids being compared should~ be recorded and~kept the same if possible.
; ~ The Broo~field LVT Viscometer with the UL (Ultra-Low viscosity~ adapter is especially suitable for this application. The UL a~dapter provides amplifyin~ effects which .- : : :
makes poss~ible measurements ~ith a reproducibility of 0.2;centipoises (cps)~ in the ultra-low viscosity ran~e of ~; û to 10 cps. Calibration of the instrument showed an average * trademark ,: :
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(5792) error of +0.2 cps at both ends of the shear rate range (10 sec~l and 70 sec~l). The shear rate on the instrument can be varied from 73.42 to 0.36 sec 1, which covers the range of shear encountered underground in the flooding process ~typically 10 sec 1), Other measuring devices such as capillary viscometers, plate and cone viscometers, and concentric cylinders can be used as appropriate.
- Some polymer solutions will exhibit thixotropic properties, characterized by the ability of a solution to become fluid when subjected to shaking, stirring, or other stress and then return to a gel when allowed to stand. Common examples of this are mayonnaise and paint. Thixotropy is also desirable for polymer solutions used in enhanced oil recovery, in which the solution is more fluid to facilitate pumping but becomeæ more viscous once it enters the oil-bearing formation.
-~ Non-Newtonian fluids are those in which a change in the rate of shear is not proportional to a change in the shear stress. For such fluids, the relationship between sheer rate and shear stress is sometimes determined at several rates of shear. Although the polymeric solutions in this invention may ~:
~;~ be non-Newtonian, shear rates which are obtained using a single ; ; set of conditions for shear stress will usually be sufficient to use as a basis of comparison to determine any change in viscosity. Additional measurements of shear rate with d~ifferent shear forces can be made if desired. Thus for these - ~ purposes, all comparisons ar`e made as if the fluids being measured behaved as Newtonian fluids. Procedures for ~ , :
~ determining viscosity are easily within the skill of the - analytical chemist, and more detailed guidelines can be found in textbooks, journals, and viscometer manufacturers' instructions.
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(5792) For ~he purposes of this invention, a change in measured viscosity of about 10 percent is considered to be very - signi~icant when comparing a test polymer solution to a control solution. Since commonly-available equipment is incapable of accurately measuring the weight of polymers with a molecular weight approaching one million, the change in the polymer was measured indirectly by determining intrinsic viscosity.
The mo~t common method of estimating the molecular weight of a polymer in solution is the use of "intrinsic viscosity" lN]. The intrinsic viscosity "[N]" can be related to the molecular weight of the polymer by means of the Mark, Houwink~ and Sakurada equation:
N] = KMa where K and a are constants being a function of the polymer type, temperature, and solvent. (This equation is discussed in more detail in Billmeyer (see belowl.

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~, . -The constants are initially determined by measuring polymers of known molecular weight. The determination of [N]
is-made by capillary viscometry of dilute polymer solutions at several concentrations. Viscosity data is extrapolated to zero concentration in order to produce a value related to molecular weight at a constant polymer ~ype, solvent, and temperature.
Even if constants are not known and the absolute : ~alues of molecular weight are unknown, the procedure is still - useful because the vaiue o~ [N] is directly proport;onal to a low power of thc molecular weight. For a solvent-temperature-polymer system that does not have the constants available, the values of [N] can be used to determine increases or decreases :: .

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(5792) of molecular weight, but not the actual value~. This concept is discussed further in a popular text (Billmeyer, Jr., F.~, Textbook of Polymer Science, 3rd Ed., New York: Interscience Publishers. 1965; pp. 79-85). Since only relative changes in molecular weight need to be determined, this procedure is satisfactory.

icroorganisms The microorganisms useful in this invention will have the capability of increasing or at least stabili7ing the viscosity of preformed polymers in solution.
In the broadest aspect of the invention, a suitable microorganism can be chosen by selecting one or more candidates and performing the screening test described below for determin;ng the effect of the microorganism on the polymer solution. Candidate microorganisms can be found almost anywhere. Soil samples and plants are logical locations, ~s well as subterranean and surface water, Oxygen availability should not be a limiting factor in the selection, since both aerobes and anaerobes are useful. Existing cultures of microorganisms can, of course, be tested for utility in this invention.
~ lasses of microorganisms contemplated as useful in this invention include phototrophic bacteria, gliding bacteria, sheathed bacteria, budding or appendaged bacteria, spiral and curved bacteria, gram-negative aerobic rods and cocci, gram-negative facultatively anaerobic rods, gram-negative anaerobic bacteria, gram-negative cocci and coccobaccilli, gram-negative anaerobic cocc;, gram-negative chemolithotrophic bacteria, methane-producing bacteria, gram-positive cocci, endospore-forming rods and cocci, gram-posi~ive, asporogenous rod-shaped bacteria, and . ~ .
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(5792) actinomycetes and related organismsO Those classes unlikely to be useful in this invention include rickettsias and mycoplasmas. Further information on the characteristics of each of these classe~ can be found in Be~gyls Manual f Determinative Bacteriolo~y ~8th Ed.) R.E. Buchanan and N.E.
Gibbons, Co-editors (1974).
Once the sample has been obtained, the microorganism should be isolated and propagated on one or more types of laboratory media using standflrd techniques.

Process The invention may be practiced using any production methods suitable for microbiological synthesis. Conventional methods used in the art are divided into two categories: batch and continuous. In a batch process all of the starting materials including the microorganisms are placed in a vessel where they remain until the desired product is formed, whereupon the vessel is emptied and the product is separated.
In a continuous process the raw materials are added and the product is withdrawn at a steady rate. A continuous method is preferred for making or treating large amounts of material, although batch processes are especially useful when close control over the process conditions is desired.
The process is typically operated at condi~ions which are optimal for ~rowth of the microorganism, since the maximum results are obtained at a hi~h metabolic rate. These op~imal . conditions are usually similar to those found in the microorganism's natural environment. The environment is duplicated i~ possible to provide the same temperature, pH, salinity~ trace elements, and other materials.

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(5792) If the environment cannot be readily duplicated, a standard nutrient media should be used to provide water, sugars, amino acids, vitamins, minerals, and trace elements.
Such media are available at biological supply houses.
The optimal range of pH and temperature for rapid growth~ as well as the range of tolerable conditions, can easily be determined by common tests known to those in the art. A more detailed description of these tests is given in "Growth", Ralph N. Costilow, Ed. Manual of Methods for General Bacteriolo~y pp. 65-179, (1981).

Screening Procedure for Microbial Viscosity Enhancement The following procedure can be used to screen candidate polymers to determine if a given microorganism will enhance the viscosity o a solution of that polymer. It can also be used to screen candidate microorganisms to determine if they wiIl enhance the viscosity of a given polymer, The procedure can also be used to screen entirely new combinations of polymers and microorganisms.
A. _reparation of Culture. A growing culture of the microorganism is prepared in a suitable growth medi~m. The specific pH and ingredients of the medium will vary depending upon the requirements of the particular microorganism. This -culture is preferably incubated for twenty-four hours at the organismls optimum growth temperature.
B Inoculation of the Polymer Solution. The polymer solution i5 preEerably concentrated enough to provide measurable viscosities for the viscosity test, but sufficiently dilute so that the amount of polymer is not toxic to the microorganism.
The polymer solution can be sterilized by steam or other means to avoid the effects of competing growth of undesired microbial contaminants. A basal salts solution is optionally added to 13.

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(5792) the polymer to assure that essential nutrients and mineral~ for the microorganismO
The growing cell culture can then be centrifuged, washed to remove any residual growth medium, and resuspended in a minimal amount of distilled water. For optimal results, a cell count is performed to determine the concentration of cells. A measured amount of inoculum, containing a given concentration oE cells, is then added to the solution containing the preformed polymer. A control solution is al80 prepared which has the same concentration of polymer solution and basal salts, but does not contain any microorganisms. An equivalent volume of sterile distilled water i~ added to the control to match the volume of inoculum added to the solutions containing the prefermed polymer.
C. Incubation of_the Solution. The control and the polymer solution with the microorganism are incubated at the optimum growth temperature for the microorganism. A sample of the solution can be removed periodically to show trends in any viscosity change, if desired. Definitive results are typically Obeained after ao incubation of 2 to 7 days.
After incubation, the microorganisms are preferably remoYed by centrifugation (or other methods compatible with the .
polymer and microorganism), leaving a microorganism-free ~solution~of the polymer.
D. Determination of Chan~es in Viscosity.
The viscosity of the microorganism-free solution can .
~ ~ be determined by the methods discussed above, such as a , Brookfield visco=eter with an ultra-low viscosity cell which will produce viscosi~y data (centipoise) at a variety of shear rates. The ViSCOsity of the test solution is compared to the viscosity of the con~rol solution. If the viscosity of the ~ .
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SPECIFIC EMBODIMENTS

Several microorganisms were screened to determine their effect on polymer solutions, using the following general procedure except where specifically noted.

' Preparation of a Medium. A basal salts medium was prepared at a double-strength concentration for later dilution with the appropriate polymer solution. The basal salts solution consisted of the following:
~ Yeast extract O.l g - ~ K~U PO4 1.0 g KH2 P4 1.0 g (NH4) 2S4 ~ ~ o Ca~C12 2H20 Oo l g Deionized H20 500 ml ,: :
The exact composition of the basai salts medium is usually not critical9 and~it can be altered depending upon the equirements~of the microorganism~being tested. The same basal salts medium shoùld be used throughout a similar series of viscosity tests9 however,~because the presence Oe salts can affect the viscosity characte;ristics of a polymer in solution.
The CaC12 2H20 was autoclaved separately to avoid pre~cipitation with the other components upon heating.
After both solutions had cooled to room temperature, the CaC12 2H20 was added to the other ingredients. The ~ ba~sal salts medium was checked for purity by streaking an -'~
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(5792) aliquot onto a nutrient agar plate and incubating the plate at 3~C Eor 24 hours.

Preparation of a Culture. Bacteria and fungi to be screened were grown on nutrient agar slants and Sabouraud dextrose agar slants, respectively. The microorganisms were incubated at 30C for 24 hours, aerobically and/or anaerobically depending on their physiological properties. Culture purity was determined via the gram stain and microscopic examination.
Five ml of the basal salts medium were added to each slant and the organisms were removed from the surface by vortexing. Five hundredths of a milliliter of the cell suspension was used as the inoculum.
'` ' Pre~ration of the Polymer Solution. A quantity of the polymer was added to deionized water to achieve a concentration of 2400 ppm (weight to volume). The polymer solution was adjusted to pH 7.0 and was s~team sterilized at 15 psi nd 121C for 60 minutes. The solution was then tested for purity as described for the basal salts solution.

Incubation.~ The basal salts solution and polymer solution were mixed in a 1:1 ratio by volume to provide a tes~ solution of five ml. Five hundredths of a milliliter of microbial .
suspension (inoculum) was added to each of ~hree tubes. The tubes were incubated for 14 days under conditions described for the inoculum preparation. After incubation each tube was examined for turbidity indicative of microbial growth.

IntrInsic Viscosity. For these experiments, results were used for comparative changes of molecular weights. Low 16.

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(5792) molecular weight metabolic products were not removed and were assumed to make no contribution to viscosity. Because of the washing procedure to remove the microbial cells from the polymer solution, any viscosity change can be a~tributed to an alteration of the polymer itself and not to the presence of biological residue. The temperature for the intrinsic viscosity determination was 25C.

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A gram negative rod characterized as a strain from the genus ~ was isolated from oil field produced water and was assigned code number M06882. In earlier lab experiments this strain had demonstrated the ability to use the partially hydrolyzed polyacrylamide, Dow Pusher(R) 500, as its sole carbon source for growth.
The media used in this experiment were prepared in two parts. A first polymer solution was made by dissolving Dow Pusher(R) 500, as obtained commercially in distilled water at a concentration of 2400 ppm (weight to volume) and pH 7Ø The second solution was made in the same way, but af~er purifying the polymer by alcohol extraction. Both solutions were stirred for 24 hours, weighed before sterilization, and then autoclaved (sterilized) for 1 hour at 121C and 15 psi. All water lost due to autoclaving was returned by adding sterile distllled water~until the polymer solutions reached their original weight.
A basal salts solution was prepared at a double concentration, as explained above. It contained 0.02% yeast extract manufactured by BBL (a division of 8ecton, Dickinson &
Company of Cokeysville, MD), 0.2% KH2P04, 0.2% K2HP04, 0.1% (NH4)2 S04, and 0. ~ CaC122H20 in distilled water at pH 7Ø The CaC12 was made as a separate stock 17.

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(5792) æolution and added to the salts solution after both were sterilized and cooled to room temperature.
The two separate Dow Pusher(R) 500/basal salts solutions for this experiment were made by aseptically mixing 1:1 solutions of basal salts medium (2X) and 2400 ppm (w/v) polymer solution.
The Enterobacter M06882 culture was grown aerobically on a nutrient agar (Difco) slant at 30C for 24 hours. The cells were harvested by adding 5 ml of sterile basal salts solution to the test tube slant and vortexing the tube gently.
This cell suspension was used as the inoculum for this experiment.
All bottles were incubated at 30C for fourteen days. Aerobic incubation included rotary shaking of the flasks at 200 rpm. Anaerobic incubation was carried out in an anaerobic chamber system ~manufactured by Forma Scientific).
Control solutions were incubated both aerobically and anaerobically.
After incubation, all test solutions and,controls were centrifuged (lO,000 x g, 30C, 20 min) and the supernatant aseptically decanted into clean, sterile sample bottles. The viscosities of the solutions were measured.
The molecular weight of the Dow Pusher~R) 500 was assumed to be 3.4 x 106, based upon published data (F.D.
Martin and J.S. Ward, Polymer ~ nts, Vol. 22, No. 2, ~merican Chemical Society ~eeting, August, 1981, p.24). The control solution viscosity was also assumed to be constant.
~etailed data showing measured viscosi~y~ intrinsic viscosity, ànd estimated molecular weight of the polymer for control solutlon A and Examples 1 and 2 are in Table 1.
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(5792) Table 1 Enterobacter M06882 with Dow Pusher(R) 500 Intrinsic Measured Viscosity Viscosi~y (cps) Estimated Example Incubation [N]10 sec~l 70 sec~l Mol. Wt.
A. Aerobic 16.6 9.7 7.0 3.4 x 106 1. Aerobic 18.1 9.2 6.3 3.7 x 106

2. Anaerobic 27.6 17.1 7.3 5.7 x 106 Compared to the control, the organism causes an - increase in viscosity or stabilizes the purified polymer from -- decomposition over the 14 days. Under anaerobic conditions, Enterobacter M06882 increases the apparent molecular weight of Dow Pusher(R) 500 from 3.4 x 106 to 5.7 x 106, an increase of about 68%. Estimates of molecular weight were made from changes in intrinsic viscosity.
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EXAMPLES_5-8 - ~ The procedures above were repeated to determine changes in intrinsic viscosity as dlscussed above. All conditions were the same except where noted.
- Table 2 summarizes the intrinsic viscosity results of these solutions incubated with Enterobacter M06882 for 2 veeks. Relative viscosity increases were found in all samples tested. The greatest~enhancement in solution viscosity was ; with the samples that were incubated anaerobically. Because a control was not available to compare the effec~s of a purified polymer under anaerobic incubation, the effects of puriEication were deemed secondary. Examples 2 and 6 were therefore compared to Control C, the closest comparison.
The intrinsic viscosity data from Examples 1-4 and Controls A and B are also shown in Table 2.

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(5792) Table 2 Enterobacter M06882_and Polyacr~l~m de*
r ' Incubation Intrinsic ~0 Increase Exa~le_ _Polymer Condi~ions __ Vis~ yL_____Viscosit~
A. Pure Aerobic 16.6 CONTROL
B. Comm. Aerobic 15.5 CONTROL
C. Comm. Anaerobic 16.9 CONTROL
_________ ______________________________________________ 1. Pure Aerobic 18.1 9 2. Pure Anaerobic 27.6 63

3. 50mm. Aerobic 17.0 10

4. Comm. Anaerobic 26.6 57

5. Pure Aerobic 18.1 9

6. Pure Anaerobic ~17.8 5

7. Comm. Aerobic 18.5 16

8. Comm. Anaerobic 19.1 18 *Dow PushertR) 500: 'IComm.'' means as commercially obtained;
Pure" means the polymer was purified by extraction ~; with methanol.
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Eight st~ains of bacteria in addition to Enterobacter M06882 were chosen for testing. All were capable of growing aerobically and/or anaerobically on various water-soluble polymers. The nine strains are identified by the following reference numbers:

Gram negatIve rods: M06882 P040~2 Gram po~itive cocci: M06682 M06182, ` Gram positive rod: 16782 The organisms P04082, P03482, and P04282 were laboratory contaminants isolated from aqueous polymer solutions. All other bacteria were isolated from oilfield produced water and ;~ drilling muds.
All strains (except M06182) were grown aerobically in ~; nutrient broth (Difco) at 30C for 24 hours. Organism M06182 was incubated anaerobically at 30C for 24 hours using thioglycollate broth.
After~incubation, the bacteria were washed three times by centrifugation (5,000 x g, 5C, 10 min) with sterile distilled water. The washed cells were resuspended in minimal sterile distilled water. Cell counts were done on each cell ` suspension using a Petrof-Hausser counting chamber.
Medis were prepared for this experiment in two parts.
Polymer solutions were made in dis~illed water at a concentration of 2400 ppm tw/v) and pH 7Ø The polymers in Table 3 were used in their commercial form and after purification by extration.

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7 ~50 (5792) Table 3 Polymer Source Polyacrylamide, hydrolyzed Dow Pusher(~
Polyvinyl alcohol Polysciences, Inc., Cat. #2815 Poly~AMPS] poly(2 acrylamido-2-methyl propanesulfonic acid) from Lubrizol Corporation Xanthan gum Xanflood(R); Kelco Hydroxyethylcellulose Natrosol 250 HHR, from Hercules, Inc.
Carboxymethylcellulose CMC 9H4 from Hercules, Inc.
Glucan Actigum CS 11-L obtained from Jetco Chemicals, Inc.
Polyacrylamide synthesized unhydrolyzed polyacrylamide; moIecular weight of 3.5 x 10 Poly(acrylic acid) Scientific Polymer Products, Inc., catalog All solutions were stirred for 24 hours, weighed, and then autoclaved (sterilized) for 1 hour at 121C and 15 psi.
All water lost due to autoclaving was returned by adding sterile distilled water~until the polymer solutions reached their original weight.
A basal salts medium was prepared as described in Example~l. Eighteen differene~polymer media for~this exper~iment were ma~de by aseptica~lly mixing 1:1 (v/v) solutions -~ ~
of basal salts medium and 2400 ppm polymer solution.
Fifty ml~aliquots of~polymer media were aseptically tran~sferred to clean, sterile 150 ml Erlenmeyer flasks. Each ; Elask~(except controls) was: inoculated to a concentration of 103 bacteria/ml with the appropriate cell suspenslon.
Control~s were inoculated wi~th equivalent volumes of sterile :~
~ distilled water.
.:
~: :
, ~

22.
.

7~5~ ~

(5792) All flasks were incubated at 30C for two weeks.
Aerobic incubation included rotary shaking of the flasks at 200 rpm, and anaerobic incubation was conduc~ed in an anaerobic chamber system. Controls ~ere incubated aerobically.
After incubation, all test solutions and controls were centrifuged (10,000 x g, 30C, 20 min) and the supernatant aseptically decanted into a clean, sterile sample bottle.
Apparent viscosity determinations were made using a Brooksfield viscometer. Table 4 s~ows the results for Examples 9 to 130, and also incorporates data from the Examples 1 to 8.
: ' Selected Microbe/Polymer Combinations Percent Incu- Change in ExamplePolymer Or~anism bationl Viscosity2 1Polyacrylamide3, puri~ied MO6882 A 9.
2 " " MO6882 ~n 63.
;~ 3Polyacrylamide3 (comm.) MO6882 A 10.
4 " " MO6882 An 57.
5PolyacryIamide3, purified MO6882 A 9.
6 " " MO6882 A 5.0 "
7Polyacryl;amide' (comm.) MO6882 A 16.
8 " MO6882 An 18,0

9 " P04082 A -8.0 :,~
" P04082 An +3.5 1l " P04282 A -4.4 ~ ~ I2 " P04282 An +4.4 ; 13 ll 16782 A
14 " ~ 1~782 An -28.3 " 20582 A -~6.2 ,:
23.

~ '71~LS~3 ~

(5792) TABLE 4 (continued) Selected Microbe/Po~,ymer Combinations Percent Exam~le . Polymer Organism bation Viscosity2 16 Polyacrylamide3 (comm.) 20582 An ~4.4 17 " (pu~ified)4 P04282 A -1.0 18 " P04282 An +35.6 19 "
P04082 A +4.8 " P04082 An +9.6 21 Polyvinyl Alcohol M06682 An -7.7 22 " MO6682 A 0 23 " M06882 A 0 24 " MO6882 : An 0 " P04082 A 0 26 " PO4082 An +7.7 27 " 16782 A 0 28 " 16782 An -7.7 29 " 20582 A -7.7 ., ~ : 3~n ~ : 20582 An -7.7 3I " ~ P04282 A +7.7 : 32 " ~ P04282 An +7.7 33~ Poly~vinyl Alcohol~(purified) M06682 A 0 :: 34 " : ~ ~M06882 A -7.7 " ~ MQ6882 An 0 36 " P04082 A 0 37 ~ Po4082 An 7.7 38 : " ~ P034B2 A 0 39 " ; PO3482 An -7.7 ~ " P04282 A 0 :41 " PO4282 An +7.7 ~ :
'~: :
:~ 24.

7~ 15~ ~
(5792) TABLX 4 (continued) Selected Microbe/Polymer Combinations Percen t Example ~ Or~an i sm ba-t i onVi sc~2 42 Poly (AMPS) M06882 An -3.8 43 " M06882 A +0.6 44 " P04082 A -8.3 " P04082 An +1.9 46 " P04282 An 0 47 " M06682 A +7.0 48 Poly(AMPS), purified6 M06682 A -1.9 49 " M06682 An -0.5 " M06882 A -12.9 51 " M06882 An -10.0 52 " P04082 A -29.7 53~ ;" P04082 An -29.2 54 ~" P03482 A -25.4 !I P03482 An -23.4 56 " ~ P04282 A -27.3 57~ " P04282 An -19.6 .
58~ Xant~an Gum P04082 An -3.0 59 ~ " ~ P04282 A -3,0 ;60 " ~ ~ P.04282 An -6.1 61 ~ 20582 An -3.0 62 ~Xanth~an ~um, purified4 P04082 An 0 ; 63 " ~ P04082 A +6.7 64 " 16782 An 0 ~ 65 i' ~ ~16782 A ~6.7 : .
~ 25.

7~ ~5~
(5792) TABLE 4 (continued) Sele ~

Percent Example Polymer Or~anism bation Viscosit~2 66 Hydroxyethylcellulose M06882 A -10.7 67 " MO6882 An -10.7 68 " . P04082 A 0 69 " PO4082 An -7.1 " P04282 An -4.3 71 " (purified)4 M06882 A -10.0 72 " MO6882 An -13.3 73 " P04082 A -16.7 74 PO4082 An -3.3 " P04282 An -6.7 76 Carboxymet~ylcellulose M06882 A -8.3 77: " P04082 A -11.1 78 " : ~ P04282 An -11.1 79~ "~(purified)4~ M06782 A -3.3 ~ MO6782 An -10.0 81 " M06882 A -3.3 8~ P04082 A -3.3 83 " ~ ~ PO4082 An O
84 :~ P04282 An -6.7 8:~ : Glucan M06882 A -10.5 86 : :: MO6882 An -6.7 ;87 ~ : P04082 A -7.7 88 ~ PO4082 An -3.4 89 " ~ P04282 A +15.9 :90 ~ " ~ 16782 A +17.4 91 " : 20582 A ~16.1 26.

7~

(5792) TABLE 4 (continued) Selected Microbe!Polymer Combinations Percen t ExamE~le Poly~ Or~anism bationViScosit~2 92 Glucan P04282 An -17.2 93 " 16782 An -18.1 94 " 20582 An -19.8 " (purified)4 M06882 A -18.2 96 " M06882 An~34.7 97 " P04082 A -8.5 g8 " P04082 An+51.4 nn "
77 P04282 A ~19.4 100 " P04282 An -13.8 101 ~ " P03482 A ~33.4 : io~ ~ 16782 An -13.0 103 " 16782 A +46.6 104 " 20582 An -13.6 105 " 20582 A +16.0 106 Polyacrylamide5 M06882 An -5.3 , :
107 " P04802 A ~5.8 108 " ~ P~4802 An 0 109 " ; P04282 A -10.5 110 " PO4282 An -5.3 111 " M06182 An -10.5 112 Polyacrylamide (purified)4 M06882A -13.6 ~: ::
113~ " P04082 A -~7.1 1 114 " PO4082 An -4.5 115 " P03482 A -18.2 ~: :
116 " PO3482 An -4.5 117 " P04282 A -4.5 : 118 ll PO4282 An -9.1 27.
~ ~ , ~ ~L~7~

(5792) TABLE 4 (continued) Selected Microbe ~ mbinations Percent Ex~ple Polymer Or~anism b~tionVi~c~ 2 119 Polyacrylic Acid7 M06882 A -3.3 120 " M06882 An +3.3 1~1 " P04082 A -3.3 122 " PO4082 An -3.3 123 " P03482 An -3.3 124 " P04282 An ~16.7 125 " (purified) M06882 A -3.3 126 " MO6882 An -6. 7 ; 127 " P040g2 A -3.3 128 " PO4082 An -6.7 ~- 129 " P04282 An -3.3 ~130 " PO4282 A +16.7 1 "A" denotes Aerobic; "An" denotes anaerobic 2 Intrinsic viscosity; indicates relative change in molecular we1gh~ of the polymer compared to the control 3 Dow Pusher(R) 500, a partially-hydrolyzed a~rylamide.
;~ 4 Purified by~extraction with methanol ., r ' Synthesized in;~Sohio~laboratories; unhydrolyzed polyacrylamide with 3 molecular weight of 3~.5 x 105.
6 ~ Purified by ~extraction~ with isopropanol.
7 Purified by ext~raction with acetonitrile.

, .

~ 2~ .
.

lS~) ~
(5792) Microbial Enhancement o~ Polymer Solution Viscosity Several samples tested in this polymer/bacteria screen showed solution viscosity increases after 2 weeks of incubation. Some of the samples that showed microbial enhancement of polymer solution viscosity can be found in Table 5, grouped according to the code number for the bacterlum.

;` ' -' ~ ~

' ::
` ' 29 .
, 7~5~ ~

(5792 TABLE_5 Percent Example ~ Or~anism bationViSco~it 2 1 Polyacrylamide3, purified MO6882 A ~9.
" MO6882 An ~63.

3 Polyacrylamide3 (comm.) MO6882 A ~190 7 ,, ,' MO6882 An ~16 8 " MO6882 An tl8.o 43 Poly(AMPS) MO6882 A ~0 6 96 Glucan (purified)4 M0S882An +34 7 120 Polyacrylic Acid MO6882 An +3.3 Xanthan Gum, purified4 16782 A +6.7 ~ 90 Glucan 16782 A ~17 4 - 103 Glucan (purified)4 16782 A +46 6 47 Poly(AMPS) M06682 A +7.0 ~- 15 Polyacrylamide, (Dow)3 20582 A +6~2 16 ' 20582 on +4.4 105 '' 255882_ A +16.1 101 : Glucan (purified)4 P03482 A +33.4 1:0 Polyacrylamide3 P04082 An +3 5 19 Polyacrylamide (purified)3 P04082A +4 8 :20 " " P04082 An ~9~6 26 Polyvinyl Alcohol PO4082 An +7 7 : 45 Poly~AMPS) PO408:2 An +1 9 ~ 63: Xanthan Gum, purified4 po4082 A +6 7 -~ 98 Glucan (purified)4 : P04082 An+51 4 ~ 12 Po7yacrylamide3 P04282 An ~4.4 ;. 18 Polyacrylamide (purified)3 P04282An +35.6 31 Polyvinyl Alcohol P04282- A +7 7 32 "~ P04282 An ~7 7 41 " (purified):7 PO4282 An +7.7 89 Glucan :: ~ P04282 A +15.9 99~ Glucan tpurified)4 P04282 A +19,4 124 Polyacrylir Acid : P04282 An +16.7 130 ~ " (purified) : PO4282 A +16.7 " denotes~A ~ An"~denotes an~erobic Intrinsic viscosity; indicates percent change in molecular we~ight of the polymer relative to the control : 3 Dow Pusher~R)~ 500.
4 Purified by extraction with methanol 7 Purified by:extraction with ace~onitrile.
--------------_______~_________ ___ ~:
3~.
.

71L~5() ~
(5792) Prior to this ~pplication or patent, the microo~gan;sms in Table 6 were deposited with the Americ~n Type Culture Collection (ATCC) in Rockville, Maryland, under an agreement whereby they would become accessible to the public upon ~he issuance o letters patent. A unique number is ~ssigned to ~ach microorganism culture deposited with the ATCC.

Table 6 Code Number vs. ATCC Number : ~ MO6882 39553 _ 2û582 39554 `; MO6182 _39559__ , :~ :
'~
-``

;' ' 31.

Claims (35)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows.

1. A method for increasing the viscosity of a solution of preformed polymers, the method comprising combining, under conditions favorable to microbial growth, (a) an aqueous solution of preformed polymers, and (b) a microorganism incapable of de novo synthesis of said polymers, said microorganism characterized as demonstrating the capability of increasing the viscosity of said polymer solution in the following screening procedure:
(i) preparing a growing culture of the microorganism;
(ii) preparing an aqueous solution of the preformed polymers and adding nutrients and minerals required for microbial growth;
(iii) separating that solution into two portions, a test and a control, both portions lacking any substrate except the preformed polymer and thereby lacking a utilizable substrate to enable synthesis of any other polymer;
(iv) inoculating the test solution with the culture of the microorganism and incubating the test and control solutions; and (v) measuring the viscosities of both test and control solutions after incubation to determine if the test solution is relatively more viscous than the control.

2. The method of claim 1 in which the microorganism is a bacterium.

3. The method of claim 2 in which the bacterium is selected from the group consisting of gram negative rods, gram positive rods, and gram positive cocci.

4. The method of claim 1 in which the polymer is a biopolymer.

5. The method of claim 1 in which the polymer is a synthetic polymer.

6. The method of claim 1 in which the polymer is selected from the group consisting of guar gum, hydroxypropyl guar, sodium carboxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl hydroxyethyl cellulose, xanthan gum, schleroglucan, locust bean gum, polyacrylamide, hydrolyzed polyacrylamide poly(acrylic acid) and salts, poly(2-acrylamido-2-methyl propane sulfonic acid) and salts, poly(acrylic acid-co-acrylate ester), poly(vinyl pyrrolidone), cellulose sulfate esters, poly(ethylene oxide), poly(vinyl alcohol), polyamine, poly(vinyl acetate-co-maleic anhydride), and poly(styrene sulfonic acid) and salts.

7. A polymer solution having enhanced viscosity characteristics, said polymer solution produced by combining, at conditions conducive to microbial growth, an aqueous solution of a preformed polymer with a microorganism incapable of de novo synthesis of said polymers but having the capability of increasing the viscosity of said polymer solution, said capability determined by the following screening procedure:
(i) preparing a growing culture of the microorganism;
(ii) preparing an aqueous solution of the preformed polymers and adding nutrients and minerals required for microbial growth;
(iii) separating that solution into two portions, a test and a control, both portions lacking any substrate except the preformed polymer and thereby lacking a utilizable substrate to enable synthesis of any other polymer;
(iv) inoculating the test solution with the culture of the microorganism and incubating the test and control solutions; and (v) measuring the viscosities of both test and control solutions after incubation to determine if the test solution is relatively more viscous than the control.

8. The solution of claim 7 in which the microorganism is subsequently removed from the polymer solution.

9. The solution of claim 7 in which the polymer is a biopolymer.

10. The solution of claim 7 in which the polymer is a synthetic polymer.

11. The solution of claim 7 in which the polymer is selected from the group consisting of guar gum, hydroxypropyl guar, sodium carboxymethyl cellulose, carboxymethyl cellulose, glucan, hydroxyethyl cellulose, carboxymethyl hydroxyethyl cellulose, xanthan gum, schleroylucan, locust bean gum, polyacrylamide, hydrolyzed polyacrylamide, poly(acrylic acid) and salts, poly(2-acrylamido-2-methyl propane sulfonic acid) and salts, poly(acrylic acid-co-acrylate ester), poly(vinyl pyrrolidone), cellulose sulfate esters, poly(ethylene oxide), poly(vinyl alcohol), polyamine, poly(vinyl acetate-co-maleic anhydride), and poly(styrene sulfonic acid) and salts.

12. An aqueous solution of preformed polymers and at least one microorganism, said microorganism characterized as demonstrating the capability of increasing the viscosity of said polymer solution in the following screening procedure:
(a) preparing a growing culture of the microorganism:
(b) preparing an aqueous solution of preformed polymers and adding nutrients and minerals required for microbial growth;
(c) separating that solution into two portions, a test and a control, both portions lacking any substrate except the preformed polymer and thereby lacking a utilizable substrate to enable synthesis of any other polymer;
(d) inoculating the test solution with the culture of the microorganism and incubating the test and control solutions, and (e) measuring the viscosities of both test and control solutions after incubation to determine if the test solution is relatively more viscous than the control, said microorganism having been introduced into the solution after said screening process.

13. In a method for the enhanced recovery of oil characterized by combining preformed polymers with an aqueous fluid to form a polymer solution, introducing said polymer solution into an oil-bearing reservoir via at least one injection well, and recovering oil from a production well, the improvement comprising adding to the polymer solution a microorganism incapable of de novo synthesis of said polymers but capable of increasing the viscosity of said polymer solution.

14. The method of claim 13 in which the polymer is selected from the group consisting of guar gum, hydroxypropyl guar, sodium carboxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl hydroxyethyl cellulose, xanthan gum, glucan, locust bean gum, polyacrylamide, hydrolyzed polyacrylamide, poly(acrylic acid) and salts, poly(2-acrylamido-2-methyl propane sulfonic acid) and alts, poly(acrylic acid-co-acrylate ester), poly(vinyl pyrrolidone), cellulose sulfate esters, poly(ethylene oxide), poly(vinyl alcohol), polyamine, poly(vinyl acetate-co-maleic anhydride), and poly(styrene sulfonic acid) and salts.

15. The method of claim 14 in which the microorganism is selected from the group of bacteria: Staphylococcus sp. ATCC 39557, Enterobacter sp. ATCC 39555, Citrobacter sp. ATCC 39560, Pseudomonas sp. ATCC 39558, Pseudomonas sp. ATCC 39554, Enterobacter sp. ATCC 39553, Staphylococcus sp. ATCC 39552, Bacillus sp. ATCC 39556, and Peptococcus sp. ATCC 39559.

16. In a method for the clarification of water by flocculation, the method characterized by mixing preformed polymers with an aqueous fluid and thereby forming a floc in which particulate matter is suspended, the improvement comprising adding to the polymer a microorganism incapable of de novo synthesis of said polymers but capable of increasing the viscosity of said polymer.

17. The method of claim 16 in which the microorganism is selected from the group of bacteria: Staphylococcus sp. ATCC 39557, Enterobacter sp. ATCC 39555, Citrobacter sp. ATCC 39560, Pseudomonas sp. ATCC 39558, Pseudomonas sp. ATCC 39554, Enterobacter sp. ATCC 39553, Staphylococcus sp. ATCC 39552, Bacillus sp. ATCC 39556, and Peptococcus sp. ATCC 39559.

18. The method of claim 16 in which the polymer is polyacrylamide.

19. In a method for the manufacture of paper, the method characterized by preparing a pulp slurry and adding an aqueous solution of preformed polymers to the slurry, the improvement comprising adding to the polymer solution a microorganism incapable of de novo synthesis of said polymers but capable of increasing the viscosity of said polymer solution.

20. The method of claim 19 in which t-he microorganism is selected from the group bacteria: Staphylococcus sp.
ATCC 39557, Enterobacter sp. ATCC 39555, Citrobacter sp.
ATCC 39560, Pseudomonas sp. ATCC 39558, Pseudomonas sp.

ATCC 39554, Enterobacter sp. ATCC 39553, Staphylococcus sp. ATCC 39552, Bacillus sp. ATCC 39556, and Peptococcus sp. ATCC 39559.

21. The method of claim 19 in which the polymer is polyacrylamide.

22. A method for increasing the viscosity of a solution of preformed polymers, the method comprising combining, under conditions favorable to microbial growth, (a) an aqueous solution of preformed polymers, and (b) a microorganism incapable of de novo synthesis of said polymers, said microorganism characterized as demonstrating the capability of increasing the viscosity of said polymer solution in the following screening procedure:
(i) preparing a growing culture of the microorganism;
(ii) preparing an aqueous solution of the preformed polymers and adding nutrients and minerals required for microbial growth;
(iii) separating that solution into two portions: a test and a control;
(iv) inoculating the test solution with the culture of the microorganism and incubating the test and control solutions;
(v) measuring the viscosities of both test and control solutions after incubation to determine if the test solution is relatively more viscous than the control; and where the microorganism is a bacterium selected from the group consisting of Staphylococcus sp. ATCC 39557, Enterobacter sp. ATCC 39555, Citrobacter sp. ATCC 39560, Pseudomonas sp. ATCC 39558, Pseudomonas sp. ATCC 39554, Enterobacter sp. ATCC 39553, Staphylococcus sp. ATCC
39552, Bacillus sp. ATCC 39556, and Peptococcus sp. ATCC
39559.

23. A method for increasing the viscosity of a solution of preformed polymers, the method comprising combining, under conditions favorable to microbial growth, (a) an aqueous solution of preformed polymers, and (b) a microorganism incapable of de novo synthesis of said polymers, said microorganism characterized as demonstrating the capability of increasing the viscosity of said polymer solution in the following screening procedure:
(i) preparing a growing culture of the microorganism;
(ii) preparing an aqueous solution of the preformed polymers and adding nutrients and minerals required for microbial growth;
(iii) separating that solution into two portions, a test and a control, both portions lacking any substrate except the preformed polymer and thereby lacking a utilizable substrate to enable synthesis of any other polymer;
(iv) inoculating the test solution with the culture of the microorganism and incubating the test and control solutions; and (v) measuring the viscosities of both test and control solutions after incubation to determine if the test solution is relatively more viscous than the control;
wherein the polymer is hydrolyzed polyacrylamide and the microorganism is selected from the group consisting of Enterobacter sp. ATCC 39555, Pseudomonas sp.
ATCC 39558, Pseudomonas sp. ATCC 39554, and Enterobacter sp. ATCC 39553.

24. A method for increasing the viscosity of a solution of preformed polymers, the method comprising combining, under conditions favorable to microbial growth, (a) an aqueous solution of preformed polymers, and (b) a microorganism incapable of de novo synthesis of said polymers, said microorganism characterized as demonstrating the capability of increasing the viscosity of said polymer solution in the following screening procedure:
(i) preparing a growing culture of the microorganism;
(ii) preparing an aqueous solution of the preformed polymers and adding nutrients and minerals required for microbial growth;
(iii) separating that solution into two portions, a test and a control, both portions lacking any substrate except the preformed polymer and thereby lacking a utilizable substrate to enable synthesis of any other polymer;
(iv) inoculating the test solution with the culture of the microorganism and incubating the test and control solutions; and (v) measuring the viscosities of both test and control solutions after incubation to determine if the test solution is relatively more viscous than the control;
wherein the polymer is polyvinyl alcohol and the microorganism is selected from the group consisting of Enterobacter sp. ATCC 39555 and Pseudomonas sp. ATCC 39558.

25. A method for increasing the viscosity of a solution of preformed polymers, the method comprising combining, under conditions favorable to microbial growth, (a) an aqueous solution of preformed polymers, and (b) a microorganism incapable of de novo synthesis of said polymers, said microorganism characterized as demonstrating the capability of increasing the viscosity of said polymer solution in the following screening procedure:
(i) preparing a growing culture of the microorganism;
(ii) preparing an aqueous solution of the preformed polymers and adding nutrients and minerals required for microbial growth;

(iii) separating that solution into two portions, a test and a control, both portions lacking any substrate except the preformed polymer and thereby lacking a utilizable substrate to enable synthesis of any other polymer;
(iv) inoculating the test solution with the culture of the microorganism and incubating the test and control solutions; and (v) measuring the viscosities of both test and control solutions after incubation to determine if the test solution is relatively more viscous than the control, wherein the polymer is poly(2-acrylamido-2-methyl propane sulfonic acid) or salts thereof and the microorganism is selected from the group consisting of Enterobacter sp. ATCC 39555, Enterobacter sp. ATCC 39553, and Staphylococcus sp. ATCC 39557.

26. A method for increasing the viscosity of a solution of preformed polymers, the method comprising combining, under conditions favorable to microbial growth, (a) an aqueous solution of preformed polymers, and (b) a microorganism incapable of de novo synthesis of said polymers, said microorganism characterized as demonstrating the capability of increasing the viscosity of said polymer solution in the following screening procedure:
(i) preparing a growing culture of the microorganism;
(ii) preparing an aqueous solution of the preformed polymers and adding nutrients and minerals required for microbial growth;
separating that solution into two portions, a test and a control, both portions lacking any substrate except the preferred polymer and thereby lacking a utilizable substrate to enable synthesis of any other polymer;

(iv) inoculating the test solution with the culture of the microorganism and incubating the test and control solutions; and (v) measuring the viscosities of both test and control solutions after incubation to determine if the test solution is relatively more viscous than the control;
wherein the polymer is xanthan gum and the microorganism is selected from the group consisting of Enterobacter sp. ATCC 39555 and Bacillus sp. ATCC 39556.

27. A method for increasing the viscosity of a solution of preformed polymers, the method comprising combining, under conditions favorable to microbial growth, (a) an aqueous solution of preformed polymers, and (b) a microorganism incapable of de novo synthesis of said polymers, said microorganism characterized as demonstrating the capability of increasing the viscosity of said polymer solution in the following screening procedure:
(i) preparing a growing culture of the microorganism;
(ii) preparing an aqueous solution of the preformed polymers and adding nutrients and minerals required for microbial growth;
(iii) separating that solution into two portions, a test and a control, both portions lacking any substrate except the preformed polymer and thereby lacking a utilizable substrate to enable synthesis of any other polymer;
(iv) inoculating the test solution with the culture of the microorganism and incubating the test and control solutions; and (v) measuring the viscosities of both test and control solutions after incubation to determine if the test solution is relatively more viscous than the control;

wherein the polymer is glucan and the microorganism is selected from the group consisting of Enterobacter sp. ATCC 39553, Enterobacter sp. ATCC 39555, Pseudomonas sp. ATCC 39558, Pseudomonas sp. ATCC 39554, Bacillus sp. ATCC 39556, and Citrobacter sp. ATCC 39560.

28. A method for increasing the viscosity of a solution of preformed polymers, the method comprising combining, under conditions favorable to microbial growth, (a) an aqueous solution of preformed polymers, and (b) a microorganism incapable of de novo synthesis of said polymers, said microorganism characterized as demonstrating the capability of increasing the viscosity of said polymer solution in the following screening procedure:
(i) preparing a growing culture of the microorganism;
(ii) preparing an aqueous solution of the preformed polymers and adding nutrients and minerals required for microbial growth;
(iii) separating that solution into two portions, a test and a control, both portions lacking any substrate except the preformed polymer and thereby lacking a utilizable substrate to enable synthesis of any other polymer;
(iv) inoculating the test solution with the culture of the microorganism and incubating the test and control solutions; and (v) measuring the viscosities of both test and control solutions after incubation to determine is the test solution is relatively more viscous than the control;
wherein the polymer is poly(acrylic acid) and the microorganism is selected from the group consisting of Pseudomonas sp. ATCC 39558 and Staphylococcus sp. ATCC
39557.

29. A polymer solution having enhanced viscosity characteristics, said polymer solution produced by combining at conditions conducive to microbial growth an aqueous solution of a preformed polymer with a microorganism incapable of de novo synthesis of said polymers but having the capability of increasing the viscosity of said polymer solution, said capability determined by the following screening procedure:
(i) preparing a growing culture of the microorganism;
(ii) preparing an aqueous solution of the preformed polymers and adding nutrients and minerals required by microbial growth:
(iii) separating that solution into two portions: a test and a control;
(iv) inoculating the test solution with the culture of the microorganism and incubating the test and control solutions; and (v) measuring the viscosities of both test and control solutions after incubation to determine if the test solution is relatively more viscous than the control, and where the microorganism is a bacterium selected from the group consisting of Staphylococcus sp. ATCC 39557, Enterobacter sp. ATC 39555, Citrobacter sp. ATCC 39560, Pseudomonas sp. ATCC 39553, Pseudomonas sp. ATCC 39554, Enterobacter sp. ATCC 39553, Staphylococcus sp. ATCC
39552, Bacillus sp. ATCC 39556, and Peptococcus sp. ATCC
39559.

30. A polymer solution having enhanced viscosity characteristics, said polymer solution produced by combining at conditions conducive to microbial growth an aqueous solution of a preformed polymer with a microorganism incapable of de novo synthesis of said polymers but having the capability of increasing the viscosity of said polymer solution, said capability determined by the following screening procedure:

(i) preparing a growing culture of the microorganism;
(ii) preparing an aqueous solution of the preformed polymers and adding nutrients and minerals required for microbial growth;
(iii) separating that solution into two portions: a test and a control;
(iv) inoculating the test solution with the culture of the microorganism and incubating the test and control solutions; and (v) measuring the viscosities of both test and control solutions after incubation to determine if the test solution is relatively more viscous than the control, and where the microorganism is selected from the group of bacteria: Enterobacter sp. ATCC 39555, Pseudomonas sp. ATCC 39558, Pseudomonas sp. ATCC 39554, and Enterobacter sp. ATCC 39553, and where the polymer is hydrolyzed polyacrylamide.

31. A polymer solution having enhanced viscosity characteristics, said polymer solution produced by combining at conditions conducive to microbial growth an aqueous solution of a preformed polymer with a microorganism incapable of de novo synthesis of said polymers but having the capability of increasing the viscosity of said polymer solution, said capability determined by the following screening procedure:
(i) preparing a growing culture of the microorganism:
(ii) preparing an aqueous solution of the preformed polymers and adding nutrients and minerals required for microbial growth;
(iii) separating that solution into two portions: a test and a control;
(iv) inoculating the test solution with the culture of the microorganism and incubating the test and control solutions; and (v) measuring the viscosities of both test and control solutions after incubation to determine if the test solution is relatively more viscous than the control, and where the mircoorganism is selected from the group of bacteria: Enterobacter sp. ATCC 39555 and Pseudomonas sp. ATCC 39558, and where the polymer is poly(vinyl alcohol).

32. A polymer solution having enhanced viscosity characteristics, said polymer solution produced by combining at conditions conducive to microbial growth an aqueous solution of a preformed polymer with a microorganism incapable of de novo synthesis of said polymers but having the capability of increasing the viscosity of said polymer solution, said capability determined by the following screening procedure:
(i) preparing a growing culture of the microorganism:
(ii) preparing an aqueous solution of the preformed polymers and adding nutrients and minerals required for microbial growth;
(iii) separating that solution into two portions: a test and a control;
(iv) inoculating the test solution with the culture of the microorganism and incubating the test and control solutions; and (v) measuring the viscosities of both test and control solutions after incubation to determine if the test solution is relatively more viscous than the control, and where the microorganism is selected from the group of bacteria: Enterobacter sp. ATCC 39555, Enterobacter sp.
ATCC 39557, and Staphylococcus sp. ATCC 39553, and where the polymer is poly (2-acrylamido-2-methyl propane sulfonic acid) or a salt thereof.

33. A polymer solution having enhanced viscosity characteristics, said polymer solution produced by combining at conditions conducive to microbial growth an aqueous solution of a preformed polymer with a microorganism incapable of de novo synthesis of said polymers but having the capability of increasing the viscosity of said polymer solution, said capability determined by the following screening procedure:
(i) preparing a growing culture of the microorganism;
(ii) preparing an aqueous solution of the preformed polymers and adding nutrients and minerals required for microbial growth;
(iii) separating that solution into two portions: a test and a control;
(iv) inoculating the test solution with the culture of the microorganism and incubating the test and control solutions; and (v) measuring the viscosities of both test and control solutions after incubation to determine if the test solution is relatively more viscous than the control, and where the microorganism is selected from the group of bacteria: Enterobacter sp. ATCC 39555 and Bacillus sp.
ATCC 39556, and where the polymer is xanthan gum.

34. A polymer solution having enhanced viscosity characteristics, said polymer solution produced by combining at conditions conducive to microbial growth an aqueous solution of a preformed polymer with a microorganism incapable of de novo synthesis of said polymers but having the capability of increasing the viscosity of said polymer solution, said capability determined by the following screening procedure:
(i) preparing a growing culture of the microorganism;
(ii) preparing an aqueous solution of the preformed polymers and adding nutrients and minerals required for microbial growth;

(iii) separating that solution into two portions: a test and a control;
(iv) inoculating the test solution with the culture of the microorganism and incubating the test and control solutions; and (v) measuring the viscosities of both test and control solutions after incubation to determine if the test solution is relatively more viscous than the control, and where the microorganism is selected from the group of bacteria: Enterobacter sp. ATCC 39555, Bacillus sp. ATCC
39556, Pseudomonas sp. ATCC 39558, Pseudomonas sp. ATCC
39554, Enterobacter sp. ATCC 39553, Citrobacter sp. ATCC
39560, and where the polymer is glucan.

35. A polymer solution having enhanced viscosity characteristics, said polymer solution produced by combining at conditions conducive to microbial growth an aqueous solution of a preformed polymer with a microorganism incapable of de novo synthesis of said polymers hut having the capability of increasing the viscosity of said polymer solution, said capability determined by the following screening procedure:
(i) preparing a growing culture of the microorganism;
(ii) preparing an aqueous solution of the preformed polymers and adding nutrients and minerals required for microbial growth;
(iii) separating that solution into two portions: a test and a control;
(iv) inoculating the test solution with the culture of the microorganism and incubating the test and control solutions; and (v) measuring the viscosities of both test and control solutions after incubation to determine if the test solution is relatively more viscous than the control, and where the microorganism is selected from the group of bacteria: Pseudomonas sp. ATCC 39558 and Enterobacter sp.
ATCC 39553, and where the polymer is poly(acrylic acid).