DD280332A1 - METHOD FOR IMPLEMENTING ANAEROUS FABRIC CONVERSIONS - Google Patents

Abstract

The invention relates to a method for carrying out anaerobic Stoffwandlungen. It refers to the superimposing of anaerobic, aqueous media with a hydrophobic liquid loaded with hydrophobic-oleophilic, aerobic Gram-positive bacteria. It works to oxygenate and thus to increase the productivity of the anaerobic process. An environmentally relevant effect is also the deodorization of volatile degradation products.

Description

were selected from the stock of Stammsainmlungen. These bacteria are pre-cultured either directly on the basis of the substances contained in the tiüssigen hydrophobic phase or based on water-soluble Substtate, such as ethanol, methanol, acetate, various sugars and incorporated into the hydrophobic phase. This happens because the hydrophobic-oleophilic bacteria, when they reach the interface oil / water, pass into the oil. This is achieved by mixing, shaking or stirring the liquid, oily phase with the aqueous, bacteria-containing medium for about 10 minutes and then separating the resulting emulsion in a settling vessel or by centrifugation into the two phases again. If the growth substrate is part of the oily phase, the bacteria are in this phase from the outset and multiply there.

The hydrophobic liquid phase contains after this treatment, based on the dry matter, 0.5-10Og of the aerobic bacterial biomass in liters. The aqueous medium in which the anaerobic reaction is to take place is then, either after inert gas flushing or without, before or after inoculation with anaerobic microorganisms, before or after the addition of anaerobic subcellular reactants or without such inoculation and additives, with the bacterial hydrophobic Overlaid liquid phase. If no oxygen-expelling pretreatment of the medium has taken place, then the depletion of the oxygen contained in the medium takes place in the course of 2-24 hours. Once the medium is deoxygenated, inoculation with the anaerobes or in the presence of an autochthonous, obligate anaerobic microflora is expected to develop. The overlay should be made so that the entire surface of the anaerobic medium adjacent to the outside air is covered by the bacteria-containing hydrophobic phase (BHP). This surface should be as small as possible in relation to the total volume. The layer thickness of the BHP is 5-50mm. In the case of the metabolisation of its components, it is filled up with fresh material at longer intervals. The method can be used in alcoholic fermentation with yeasts, fungi and bacteria, in the production of lactic acid, in the acetone-butanol fermentation with clostridia and other anaerobic, reductive Stoffwandlungsprozessen. It is of particular interest in the degradation of organic matter, which involves the participation of anaerobic microorganisms and methane formation. The advantages of the method are that even in open vessels a reliable conclusion to atmospheric oxygen is achieved that the oxygen-consuming microorganisms are spatially separated from the anaerobic production strains, that they do not die because of lack of oxygen or because of the formation of toxic substances and also not, or at most to a negligible extent, to compete with their substrates. The storage in the oily phase ensures an extremely long survival time (several months to years) even at rest. Inoculation, sampling, measurements, stirring and other manipulations can be easily accomplished by puncturing the liquid topcoat without jeopardizing the anaerobic status of the major culture. A further advantage, in particular for digestion processes, is that volatile decomposition products which are troublesome due to their odor are absorbed and decomposed in the hydrophobic covering layer, in the sense of a biofilter, so that this covering layer simultaneously has a deodorizing effect. This effect can be influenced both by the thickness of the layer and by the peculiarities of the hydrophobic strains used. Strains with a broad substrate spectrum comprising hydrocarbons, carbohydrates and C i compounds are particularly suitable.

embodiments

By the following embodiments, the invention will be explained in more detail.

example 1

Each 50 ml of PBB medium (phosphate-buffered base medium) containing 0.5VoI .-% methanol and 1 mg χ I ¹ sodium resazurinate as a redox dye were overlain with 25 ml of paraffin oil !, in the oleophilic bacteria of the strain Corynebacterium spec. - IMET 11350 pre-cultured on glucose as carbon source. The entrained blind tests were overcoated with paraffin oil without microorganisms. All samples remained at 30 C without mixing.

Due to the content of sodium resazurinate, the aqueous phases were initially colored blue. Over the course of 40 hours, they were decolorized in cases where the paraffin oil used for overcoating was loaded with bacteria. This discoloration indicates that the redox potential of the aqueous medium in the oxygen consumption in the substrate oxidation (paraffin oil) by the hydrophobic microorganisms of the strain used below -15OmV (relative to the normal hydrogen electrode) dropped and thus was the prerequisite for the growth of anaerobic microorganisms.

Example 2

Each 50 ml of PBB medium, which contained 0.5% by volume of methanol, was covered with 25 ml of paraffin oil (layer thickness 10 mm), which had been coated with oleophilon bacteria of the strain Corynebacterium spec. - IMET 11347 pre-cultured on methanol as carbon source (approximately 10 g χ Γ '). In the entrained blind experiments was covered with paraffin oil without bacterial loading. All samples were left without mixing for 48 hours at 30 ° C. with the aim of producing the oxygenation described in Example 1. Thereafter, all samples were inoculated with 10 ml of an enrichment culture of Methanosarcina sp., Such that the cover layer was pierced with the pipette The cultures were measured volumetrically.

Duration of fermentation Evolved amount of gas (ml)

of Methanosarcina sp.

(H)

Without paraffin oil Paraffinölmit Bakterionbeladung IMET11347 10 27 20 40 46 68 63 83 71 99

18

42 90 114 138

The gas formed was 90% methane.

Claims (2)

1. A method for carrying out anaerobic Stoffwandlungen by microbial oxygen removal, characterized in that the aqueous anaerobic medium is overcoated with a hydrophobic, liquid at the reaction temperature phase in which aerobic, hydrophobic-olecphile, gram-positive bacteria are incorporated. 2. The method according to claim 1, characterized in that are used as hydrophobic liquids paraffins, paraffin oil, petroleum distillates vegetable and animal oils and fats and silicone oils and mixtures of such liquids. Field of application of the invention The invention relates to anaerobic fermentations or enzymatic transformations, which proceed in the absence of molecular oxygen. It serves to remove molecular oxygen from such reaction systems. Fields of application are environmental biotechnology and fermentation chemistry. Characteristics of the known prior art Anaerobic fermentations are inhibited by the presence of molecular oxygen. The target products of the fermentations are recovered either under conditions which allow the access of molecular oxygen, either not at all or with reduced yields. An example of this is alcoholic fermentation, in which, in the presence of oxygen, an inhibitory effect called Pasteur effect occurs. Only after consumption of oxygen is an intensive alcoholic fermentation possible. Another oxygen-dependent phenomenon is the dimorphism known from Mucor rouxianus. He stated that this aerobic fungus forms extensive mycelia and spores in the presence of oxygen, while in the absence of oxygen it produces yeast cells with similar activity, whose occurrence is coupled with fermentation products such as lactic acid or ethanol. The obligate anaerobes, which include methanogens such as Methanbacterium formicium, Methanosarcina barkeri and others, are used in wastewater treatment. They are capable of anaerobic digestion of organic matter to produce biogas, but only with the strict connection of oxygen. In facultative anaerobes, such as yeasts, fungi or lactic acid bacteria, the oxygen still present in the medium is eaten either by these microorganisms themselves or by an accompanying flora in the first phase of the fermentation. Only in the absence of oxygen is the main fermentation possible. The transition from pre- to main fermentation is inevitably associated with a loss of fermentable substrate (HJ Böge i, Knaur's book of biotechnology, Munich 1976). In various processes of lactic acid fermentation take over aerobic components of the mixed population or specially? Uses used aerobic starter cultures (DD-PS 221068, DD-PS 256256), the oxygen consumption. It is disadvantageous that substrate losses arise and the aerobes under Sauurstoffmange! die off, so that they are not available again if necessary. Other options, which are mainly used in obligate anaerobic processes, consist in the displacement of oxygen by inert gases, such as nitrogen, argon, CO ₂ , or the redox potential in the culture medium is lowered by the addition of sulfide, but this leads to disadvantages in the workup Batch, WE et al., Bact., Rev. 43, 260-296 (1979); Rabotnowa IL, The importance of physicochemical factors (pH and rH) for the life activity of the microorganisms, Fischer, Jena, 1963). The digestion of organic matter to biogas requires, for reasons of completion against oxygen, but also in view of the unavoidable odor nuisance, the establishment of hermetically sealed, pressure-resistant reactors, which are material-intensive and expensive. (Braun, R. "Biogas-methane fermentation of organic wastes", Springer Vienna, New York, 1982, Dubrovsky, W.S., Viestur U.E. "Methane fermentation of agricultural waste" (Russ.l.Riga 1988). Object of the invention The aim of the invention is to intensify anaerobic processes of the material conversion, to avoid substrate losses, to increase the yield of target products, to simplify reactor design and to achieve environmental friendliness. Explanation of the essence of the invention The invention is therefore an object of the invention to develop a self-regenerating system capable of auszehren the oxygen in the medium to reliably shield the anaerobic reaction chamber against the re-entry of atmospheric oxygen, while ensuring the unhindered leakage of gaseous reaction products. According to the invention, the suspension is dissolved in such a way that the medium in which the anaerobic conversion of material takes place is covered with a hydrophobic liquid, embedded in hydrophobic-oleophilic, aerobically-growing bacteria. This hydrophobic liquid may consist of paraffins preferably in the chain length range C ₁₀ -C ₈ from paraffin oil, diesel fuel, dewaxed diesel fuel, biolipid extract, vegetable oils and animal fats which are liquid at the reaction temperature. It may serve as a substrate for growth of the incorporated hydrophobic oleophilic microorganisms or for limited oxidation, or may be an inert material to microbial conversions. In the stored microorganisms are hydrophobic oleophilj bacteria from the circle of the genus Corynebacterium, Mycobacterium, Arthrobacter or Nocardia, which obtained by a known method (DD-PS 254209) from nature or