EP0885032A1

EP0885032A1 - Process for microbial decomposition of harmful substances in media charged with harmful substances, and micro-organisms suitable for this purpose

Info

Publication number: EP0885032A1
Application number: EP97906145A
Authority: EP
Inventors: Peter Bartholmes; Kerstin Heesche-Wagner; Michael Kaufmann; Thomas Schwarz
Original assignee: Bitop Gesellschaft fur Biotechnische Optimierung mbH
Current assignee: Bitop Gesellschaft fur Biotechnische Optimierung mbH
Priority date: 1996-03-01
Filing date: 1997-02-28
Publication date: 1998-12-23
Also published as: WO1997031682A1; DE19708181A1; JP2000505341A

Abstract

The invention relates to a process for microbial decomposition of harmful substances in media charged with harmful substances during cleaning of air, sewage and soil. It also relates to a device for performing said process, micro-organisms suitable for performing said process and the use thereof. The object of the invention is to improve said process in such a manner that micro-organism cultures used to break down harmful substances are established on a long-term basis, and at the same time to achieve high rates of decomposition. To attain said object, the invention proposes a process in which there is continuous decomposition fermentation in a decomposition fermenter using micro-organisms, available in the medium charged with harmful substances, and/ or a micro-organism culture added to the medium. During decomposition fermentation the concentration of harmful substances in the decomposition fermenter is controlled to make it toxin-static or toxin-dynamic using a control circuit, as a function of the vitality of the biomass. To decompose formaldehyde, the invention proposes the use of particular micro-organisms which decompose formaldehyde. To decompose phenols, the invention proposes the use of particular micro-organisms which decompose phenol.

Description

Process for the microbial degradation of pollutants in polluted media and suitable microorganisms

The invention relates to a method for microbial degradation of pollutants in pollutant-laden media in air, wastewater or soil purification and a device for carrying out this method. The invention further relates to microorganisms suitable for carrying out the method and their use.

The methods for the reduction of pollutants in polluted media (air, waste water, soil) are referred to as remediation processes. These methods include both the thermal, physical or chemical treatment of the contaminated medium and the biological elimination of pollutants, in which the pollutants contained in the medium are decomposed by the microorganisms or converted into other substances, the disposal of which is less problematic. Microorganisms suitable for the efficient degradation of pollutants must have an optimal pollutant tolerance and the highest possible genetic stability in addition to their specific degradability. In addition, suitable strains must not be pathogenic and must not form dangerous end or intermediate products.

Since natural selection has already resulted in the accumulation of microorganisms at correspondingly contaminated sites, which have special degradability for these pollutants and have a relatively good tolerance to pollutants, microorganisms belonging to the site are often used for biological pollutant elimination. However, on-site microorganisms often have the disadvantage that they are unsuitable for use in environmental engineering because of their low breakdown rates, their low toxin tolerance or their susceptibility to foreign germs Systems not suitable For this reason, more and more "special cultures" are used in microbial pollutant elimination, which have both higher degradation rates and less susceptibility to foreign germs, a relatively high level of genetic stability and / or a high toxin tolerance Special crops can achieve a certain increase in the degradation performance of the biocoenosis and a shortening of the approach tents of degradation systems

In the field of environmental biotechnology, a number of microorganisms which have been bred specifically for specific applications are commercially available. If such microorganism cultures are used in the degradation processes according to the prior art, the problem frequently arises that the life of the microorganisms used and therefore the degradation performance of the culture is limited are because the specialists die after inoculation or are displaced by other microorganisms which do not contribute to the reduction of pollutants

This is particularly true when mixtures of toxic and non-toxic substances are present in the polluted medium. If such substrate mixtures are present, the more easily degradable substances are preferably used, since this is more energy-efficient. The adapted specialists are no longer required and therefore do not develop Therefore, long-term establishment of the cultures in the state-of-the-art mining processes usually does not succeed, and for this reason the digesting fermenter in which the digesting fermentation takes place must be re-vaccinated periodically, which is time-consuming and cost-intensive and therefore uneconomical

It is therefore an object of the invention to improve the process for microbial degradation of pollutants in polluted media in such a way that long-term establishment of the microorganism cultures used for degradation of pollutants is achieved and high degradation rates are achieved at the same time. A further object of the invention is to develop microorganisms, which are suitable for carrying out the method according to the invention, and to provide their use and a device for carrying out the method

The task is solved by a process for the degradation of pollutants in pollutant-laden media during air, wastewater or soil cleaning, in which continuous degradation fermentation is carried out using contaminated pollutants

Medium existing microorganisms and / or one added to the medium Microorganism culture is carried out in a degradation fermenter, the pollutant concentration in the degradation fermenter being controlled with the aid of a control loop during the degradation fermentation

This control can be carried out either by keeping the pollutant concentration constant between an upper and a lower threshold value (f-oxinostatic fermentation) or by using the vitality of the biomass as a leader to regulate the toxin concentration (toxinodynamic fermentation) Toxinodynamic fermentation, for example, oxygen consumption or cell respiration serve as vitality parameters. The above-mentioned regulations for the pollutant concentration in the fermenter allow the selection pressure to be maintained during the process. During toxinostatic or toxinodynamic fermentation, the fermenter is used for continuous sampling for on-line purposes. Measurement of the pollutant concentration, the type of measurement of course depending on the pollutant to be detected. The control can be parameterized in such a way that when a certain threshold value is reached, it is reduced the pollutants are pumped into the reactor while the inflow of the pollutants is reduced when a second, upper concentration threshold value is reached

For example, FIG. 1 shows the phenol and formaldehyde concentration in the course of a toxinostatic fermentation. Curve A shows the measurement signal of the concentration of phenol and curve B shows the measurement signal of the concentration of formaldehyde in the fermenter. The black blocks show the duration of the pumping intervals of the substrate feed on

The process according to the invention under the control of toxinostatic fermentation brings two essential advantages for industrial pollutant degradation in a continuous reactor. On the one hand, by specifying a suitable setpoint for the pollutant concentration in the reactor outflow, prescribed receiving water limit values can be observed. On the other hand, this type of control allows high fluctuations in the pollutant concentration in the polluted medium to be buffered efficiently in the continuous operation In order to prevent microorganisms which do not contribute to the degradation of pollutants from establishing themselves in the system, the lower threshold value of the pollutant concentration in the degradation fermenter is preferably not below the okotoxicity limit of any microorganisms which are present in the degradation fermenter but which do not contribute to pollutant degradation The okotoxicity limit is the pollutant concentration at which the total metabolism of the examined biological material breaks down

In a preferred embodiment of the invention, the polluted medium contains formaldehyde and the added microorganism culture contains the microorganisms DSM 11423 and / or DSM 11424 or mutants or variants of these microorganisms

Formaldehyde in aqueous solution, usually also referred to as formahn, has an extremely toxic effect on microorganisms and is one of the best disinfectants, preservatives and stabilizers. The formaldehyde tolerance values of the microorganisms described so far are far below the formalin concentrations normally found in problematic waste water and waste Microbial degradation of formaldehyde in high concentrations has not been possible until now. When using the above-mentioned microorganisms in the process according to the invention, however, a microorganism culture is developed which is capable of formaldehyde concentrations of up to 5,500 mg / l tolerate and degrade the pollutant at high speed

In a further embodiment of the process according to the invention, the pollutant-containing medium contains phenol and the microorganism culture contains the microorganism DSM 11425 or mutants or variants of this microorganism. The degradation of formaldehyde and phenol during the same fermentation is carried out with simultaneous use of DSM 11425 with DSM 11423 and / or DSM 11424 also possible

The microorganisms DSM 11423, DSM 11424 and DSM 11425 were deposited on 21.02.1997 with the DSMZ - German Collection of Microorganisms and Cell Cultures Mascheroder Weg 1 b, D-38124 Braunschweig. The physiological and bacterological properties of these microorganisms are shown in Tables 1 and 2 referenced The microorganism DSM 11423 was isolated from a formalin-impregnated tissue sample and initially identified as Methylobacterium βxtorquens. In degradation fermentations under different conditions, DSM 11423 shows a maximum degradation rate for formaldehyde of 1612 nmol / min ^* mg and a tolerance limit for this pollutant of 10 mM. DSM 11423 has the highest degradation rate and the lowest Ks value of the formaldehyde-degrading strains investigated in the context of the invention (696 μM) and is able to reduce the formaldehyde content of a formaldehyde-contaminated medium to almost zero by degradation. The pollutant tolerance, on the other hand, is low at 10 mM (300 mg / l). In the first step, the formaldehyde is broken down by oxidation to formic acid, catalyzed by the glutathione-dependent formaldehyde dehydrogenase. The specific activity of this enzyme in the crude extract is very high at around 1.6 lU / mg protein.

The microorganism DSM 11424 was also isolated from a formalin-impregnated tissue sample and initially identified as Pseudomonas putida. When degradation was observed under various conditions, DSM 11424 showed a maximum degradation rate for formaldehyde of 784 nmol / min ^* mg and a tolerance limit for this pollutant of 100 mM. Compared to other formaldehyde-degrading strains investigated, DSM 11423 has an average degradation rate but the highest K _s value (11643 μM) and is able to decompose formaldehyde even at very high concentrations. Due to the high K _s value, the formaldehyde content of the medium can be reduced to approximately 200 mg / l by pure culture of this microorganism. As in DSM 1 1423, the formaldehyde degradation takes place in the first step via oxidation to formic acid, catalyzed by the glutathione-dependent formaldehyde dehydrogenase. The specific activity of this enzyme in the crude extract is only low.

The microorganism DSM 11425 was isolated from a soil sample and is able to convert phenol with a significantly higher degradation rate than the microorganisms on site. The partial sequencing of the 16S rRNA of this microorganism showed a similarity of 99.1% to the type strain Klebsiella oxytoca.

The aerobic phenol degradation takes place in a first step by means of an NADH- or NADPH-dependent orf / 70-hydroxylation of the phenol which is catalyzed by the phenol hydroxylase. The product is catechol, a key intermediate in most aromatics routes. Catechol is metabolized in two ways: first through the chromosome-encoded o / tΛo cleavage, and also via the plasmid-encoded mete-cleavage, the ortήo cleavage being induced by its product, cis.αs-muconic acid and the mete-cleavage by phenol. The expression of the respective enzymes can be found in the crude extract based on the different absorption maxima of the resulting products, cis.cis-muconic acid (λmax = 260 nm) and 2-hydroxymuconic acid semιaldehyde (λmax ⁼ 375 nm). Table 3 shows the specific activities and

Michaehkonstanten in the crude extract of the microorganism DSM 1 1425 shown The kinetic parameters of whole cells are 7-9 μM (K _s ), 400-500 nmol / min * mg (vmax) and 1.83 mM for the inhibition constant Ksi

In a further embodiment of the method according to the invention, the medium flowing out of the degradation fermentation is subjected to a second degradation fermentation, the lower threshold value of the pollutant concentration in the degradation fermenter being lower in the second degradation fermentation than in the first degradation fermentation. An increase in the degradation efficiency is achieved by the pollutant concentration in the first fermenter, independent of that of the second fermenter, so that an optimal enzyme induction and thus a correspondingly high degradation rate is achieved. The pollutant concentration in the second fermenter is then set so that the pollutant concentration in the process corresponds to the prescribed introduction limit

Before being added to the pollutant-laden medium, the microorganism culture is preferably cultured in a mutation fermenter containing a nutrient-rich medium and subjected to a mutagenic treatment and stabilized and then in a selection fermenter which contains a nutrient-poor medium enriched with the pollutant (s). subjected to a selection whereby part of the culture from the selection fermenter is continuously returned to the mutation fermenter until a microorganism culture with the desired pollutant degradation performance and tolerance has been established

In this embodiment of the method according to the invention, the degradation fermentation is preceded by a method for growing microorganisms which is based on the principle of evolutionary optimization. Reference is made here to the applicant's German Patent No. 195 07 103 The microorganisms DSM 11423, DSM 11424 and DSM 11425 described above are used according to the invention for the cultivation of mutants or variants. Cultivation can take place, for example, by selecting spontaneously occurring mutations. Other possibilities include, for example, mutation through the action of chemical substances and / or radioactive radiation and / or UV light. This allows mutants and variants to be obtained which have improved properties, for example with regard to the pollutant degradation performance or the pollutant tolerance.

Furthermore, the microorganisms DSM 11423 and DSM 11424 according to the invention are used as donor organisms for genetic material, in particular for inserting a gene coding for a formaldehyde dehydrogenase or formaldehyde dismutase and / or the associated promoter sequence into a microorganism or a cell. The gene is incorporated into the recipient organism using the methods customary in microbiology, e.g. using a vector. By expression of the gene incorporated in the recipient organism, larger amounts of an enzyme relevant for the degradation of pollutants, for example formaldehyde dehydrogenase, can be produced. The aforementioned microorganisms are also used to obtain a gene encoding a formaldehyde dehydrogenase or formaldehyde dismutase and / or the associated promoter sequence for the purpose of sequence analysis.

The biomass obtained by carrying out the method according to the invention can advantageously be used for / n-s / Y-z soil remediation, in which the pollutants of degradable microorganisms are broken down directly in the soil without removing the soil and thus changing the soil structure.

To achieve a further object of the invention, an apparatus for carrying out the method according to the invention is proposed which contains at least one degradation fermenter and means for regulating the pollutant concentration in the degradation fermenter or fermenters. In its simplest embodiment, the device contains a degradation fermenter and the associated means for regulating the concentration of pollutants in the fermenter, but several parallel fermenters are also conceivable, which can be loaded and inoculated with pollutant-laden medium at the same time. To carry out the method according to claim 7, two successive decomposition fermenters are provided, in which the pollutant concentration is set independently of one another by corresponding control loops. To carry out the method according to claim 8, a device is preferred which contains a mutation fermenter for the cultivation, mutagenic treatment and stabilization of the microorganism culture, a selection fermenter, means for returning part of the culture from the selection fermenter to the mutation fermenter, means for regulating the pollutant concentration in the selection fermenter contains at least one degradation fermenter and means for regulating the pollutant concentration in the degradation fermenter (s).

The essence of the invention is explained below with the aid of a few examples, without restricting the invention thereto.

example 1

A fermenter with a reactor volume greater than 10 1 is continuously fed with hospital wastewater which contains formaldehyde in fluctuating concentrations between 50 g / 1 and 200 g / 1. In addition to formaldehyde, the water contains various other organic substances. The following media components are added to the wastewater before the reactor is introduced:

NH4N03 7.6 mM

K2HP04 / KH2PO4 6.0 mM

MgSO4 ^* 7H2θ1.2 mM

CaCl2 0.9 mM N NaaCCII 0., 55 mM

ZnSθ4 0.1 mM

FeSO4 0.07 mM

The formaldehyde-containing solution introduced does not contain any viable microorganisms due to its high toxicity, but for safety reasons it is exposed to lethal doses before UV radiation is introduced. The reactor is inoculated with a mixed culture containing the microorganisms DSM 11423 and DSM 11424.

The process is carried out in the range from pH 5.0 to 8.5 and under pθ2 regulation up to 10% of the maximum oxygen saturation concentration of the waste water. Degradation fermentation takes place at temperatures between 5 and 45 ° C, in particular between 22 and 30 ° C. The culture is carried out aerobically, continuously and in a toxin-static mode: the formaldehyde concentration in the reactor is measured continuously and kept constant by regulating the inflow between an upper threshold value and a lower threshold value. This pollutant concentration requires a relatively high pollutant tolerance from the microorganisms. Microbial formaldehyde degradation has the effect that the difference between the pollutant concentration of the waste water introduced into the system and the concentration in the outlet is very high is high The water flowing out of the reactor contains a residual concentration of formaldehyde, which is completely degraded microbially in a secondary clarifier

Example 2:

A large-scale fermenter is continuously fed with industrial wastewater from bakelite production, which contains formaldehyde in fluctuating concentrations between 8 g / 1 and 12 g / 1. In addition to formaldehyde, the wastewater contains phenol in a concentration of 40 g / 1 and various Other organic components The media components specified above are added to the wastewater before the reactor is introduced. The introduced formaldehyde and phenol-containing solution contains no viable microorganisms due to its high toxicity, but it is released as a lethal dose for safety reasons before UV radiation is introduced set

The reactor is inoculated with a mixed culture that contains the microorganisms DSM 11423, DSM 11424 and DSM 11425. The degradation process is carried out as indicated above. The formaldehyde concentration in the reactor is measured continuously and is kept constant by regulating the inflow between an upper threshold value and a lower threshold value. This pollutant concentration requires a relatively high tolerance to pollutants from the microorganisms. The microbial formaldehyde degradation has the effect that the difference between the pollutant concentration of the waste water introduced into the system and the concentration in the outlet is very high. Simultaneous to formaldehyde degradation, microbiological phenol degradation takes place in the reactor. The water flowing out of the reactor contains a residual concentration of formaldehyde and / or phenol, which is broken down microbially in a secondary clarifier Example 3:

Each 10 ml medium with the composition

Peptone No. 5 5.0

Meat extract 3.0 g / pH 7.0

are incubated with 0.1 g of formalin-containing tissue in formalin containing anatomical preparations from various sampling points in 50 ml Erlenmeyer flasks at 30 ° C. with gentle swirling on a rotary shaker for 24 hours. 250 μl of this culture are inoculated in 5 ml of mineral medium with formaldehyde as the only carbon source with the following composition:

NH4N03 7.6 mM

K2HP04 / KH2P04 6.0 mM

MgSO4 * 7H2θ1.2 mM

CaCl2 0.9 mM N NaaCCII 0., 55 mM

ZnS04 0.1 mM

FeS04 0.07 mM

Formaldehyde 2.0 mM pH 7.0

After three days of incubation, the culture is transferred to 150 ml of the above medium. After another four days of incubation, a series of dilutions and a partial characterization of the colonies formed are carried out. This culture serves as the seed culture for the following toxinostatic fermentation

Over a longer period of time, a mixed culture under periodic ultraviolet radiation is optimized in a fermentation process carried out in a continuously toxinostatic manner. The formaldehyde concentration set in the fermenter via a control loop is gradually increased during this period depending on the vitality of the overall culture.

At different fermentation times, samples are taken from the fermenter and subjected to microbiological analysis according to the usual methods. terzogeπ If no increase in degradation performance and resistance can be observed, the culture is harvested and used to inoculate a degradation fermentation according to Example 1

The originally selected strains have a very high formaldehyde resistance of 500-6000 mg / l formaldehyde for naturally occurring microorganisms. During the fermentation, resistance and degradation rates of the original culture can be increased by a factor of 10 each

Example 4:

A production plant glues its products with formaldehyde- and phenol-containing adhesives. The adhesive residues are collected and regularly transported to a central biological disposal facility. Here, the waste is biologically disposed of together with other liquid formaldehyde- and / or phenol-containing waste batches from different sources. The waste stream supplied to the plant fluctuates very strongly due to the heterogeneity of the waste batches in relation to the formaldehyde and phenol concentration

The phenol index and the formaldehyde concentration are measured "on-line" and continuously in the bioreactor of the disposal system. If one of the two measurement parameters reaches the permissible upper limit concentration, the supply of pollutants into the reactor is stopped until the upper threshold value is again fallen below if the phenol index falls and / or the formaldehyde concentration to a fixed lower concentration value, this is raised again above the lower threshold value by increasing the flow rate or by additionally adding the respectively limited pollutant. In this way, despite charging the bioreactor with qualitatively very different wastewater batches degrading special culture can be stabilized

Example 5:

The formaldehyde-contaminated air in the vicinity of a production and processing facility must be cleaned in order to get below the permissible MAK values in the air. The formaldehyde pollution in the air fluctuates An air washer is used to clean the air, which removes the gaseous formaldehyde from the medium Air is transferred into the medium of water The wash water contaminated with formaldehyde is finally fed to a toxinostatically regulated biological clarification stage, where the formaldehyde is biologically eliminated. The washing water thus regenerated is then fed back to the air washer system in order to again take up formaldehyde from the air

Example 6:

Large amounts of phenol-contaminated wastewater accumulate during the renovation of former lignite mine deposits. During this renovation, groundwater and rainwater are contaminated with phenols

Usually between 500-1500 mg / l phenol index and the waste water volume flow per sanitary

3 location between 100,000 and 200,000 m / year The relatively continuously occurring wastewater flows are fed to a multi-stage treatment plant, the central and most important component of which is a toxinostatically operated bioreactor

3 a working volume of 10 m. Here the phenols contained in the wastewater are eliminated up to a lower limit concentration. The remaining phenol load is broken down in a less energy-intensive drip body biology

Example 7:

Glutaraldehyde is used in the hospital area for cleaning and disinfecting work surfaces. Running washing water contaminated with glutaraldehyde is operated in a toxinostatic manner (the standard size is the glutaraldehyde concentration)

3 Reactor with a working volume of 1 m fed Glutaraldehyde is largely biologically eliminated in the reactor and the wash water is then further treated

Example 8:

A floor contaminated with benzene is cleaned in a floor washing system. The washing water contaminated with benzene is fed to a toxinostatically operated bioreactor (standard size is the benzene concentration). After the biological removal of a large part of the benzene in the washing water, it is used again for washing the floor Example 9:

During an in-situ soil remediation, a groundwater stream contaminated with various polyaromatic hydrocarbons (PAHs) is produced. This is conveyed to the surface via groundwater lances with the aid of suction pumps and fed to a biological clarification stage operated by toxins. A sample stream is continuously withdrawn from the bioreactor and this is continuously analyzed for high-quality liquid chromatography (HPLC) coupled with fluorescence chromatography for quality and quantity of the various PAHs contained. The PAK species which is most highly concentrated in the overall spectrum of PAHs is used at all times as the controlled variable of the toxinatic control.

Table 1

DSM 11423 DSM 11424

identification

Gram staining: - Gram staining: - small round smooth medium-sized light colonies frayed colonies small coconut sticks chopsticks

API 20 NE:

nitrate

Tryptophan glucose

Arginine dihydrolase urease aesculin gelatin p-nitrophenyl-β-D-galactopyranoside. Assimilation tests glucose arabinose mannose mannitol

N-acetylglucosamine maltose gluconate + caprate + adipate + malate + + citrate + +

Phenyl lactate + + oxidase + + Table 2

Properties DSM 11425

Cell shape rods ONPG

Width μm 1.0-1.2

Long μm 1, 2-2.0 ADH

agility

Gram response - ODC

Lysis by 3% KOH +

Aminopeptidase (Cerny) + VP

Spores - H ₂ S education

Oxidase

Catalase + Simmons Citrate

Growth + anaerobic

Acid from (OF test) + phenylalanine deaminase

Glucose aerobic + glucose anaerobic + malonate utilization

Gas from glucose + acid from (ASS) + urease

Glucose +

Fructose + hydrolysis of

Xylose + gelatin

Erythπt DNA

Adonit + Tween 80

D-Mannose +

L-rhamnose +

Dulαt +

Inositol +

Sorbitol + α-methyl-D-glucoside +

Cellobiose +

Maltose +

Lactose +

D-Arabitol + Table III

specific activities and Michaelis constants in the crude extract

^l) The dehydrogenase activity was determined by subtracting the hydrolase activity (without NAD ^" in the test) from the sum of both activities (NAD ^" in the test). ^b) Low phenol: concentration on average approx. 100 mg / l phenol; High phenol: concentration 200 - 500 mg / l phenol during the entire cultivation of the cells.

Abbreviations: 2-HMS. 2-Hyo ^ oxymuconsäuresernialdehyd, n.d .. not carried out

Claims

claims

1. Process for the degradation of pollutants in polluted media in air, waste water or soil cleaning, in which continuous degradation fermentation using microorganisms present in the polluted medium and / or a microorganism culture added to the medium in one Digestion fermenter is carried out, the pollutant concentration in the degradation fermenter being controlled with the aid of a control circuit during the degradation fermentation.

2. The method according to claim 1, characterized in that the pollutant concentration in the fermenter between an upper and a lower

Threshold is kept constant.

3. The method according to claim 1, characterized in that the pollutant concentration in the degradation fermenter is controlled depending on the vitality of the biomass.

4. The method according to any one of claims 1 to 3, characterized in that the lower threshold value of the pollutant concentration in the degradation fermenter is not below the okotoxicity limit of possibly present in the degradation fermenter, but not contributing to pollutant degradation microorganisms.

5. The method according to any one of claims 1 to 4, characterized in that the contaminated medium contains formaldehyde and that the added microorganism culture contains formaldehyde-degrading microorganisms, in particular DSM 11423 and / or DSM 11424 or mutants or variants of these microorganisms.

6. The method according to any one of claims 1 to 4, characterized in that the polluted medium contains phenols and that the Mikroorganismen¬ culture contains phenol-degrading microorganisms, in particular the microorganism DSM 11425 or mutants or variants of this microorganism

7. The method according to any one of the preceding claims, characterized gekenn¬ characterized in that the medium flowing from the degradation fermentation is subjected to a second degradation fermentation, the lower threshold of the concentration of pollutants in the degradation fermenter in the second degradation fermentation being lower than in the first degradation fermentation

8. The method according to any one of the preceding claims, characterized gekenn¬ characterized in that the microorganism culture is cultivated in a mutant fermenter containing a nutrient-rich medium, subjected to a mutagenic treatment and stabilized and then in a selection fermenter, before being added to the contaminated medium a nutrient-poor medium containing the pollutant or pollutants is subjected to a selection, part of the culture from the selection fermenter being continuously returned to the mutation fermenter until a microorganism culture with the desired pollutant degradation capacity and tolerance is established Has

9 microorganism DSM 11423

10 microorganism DSM 11424

11 DSM 11425 microorganism

12 Use of a microorganism according to one of claims 9 to 11 for the cultivation of mutants or Vaπanten the same

13 Use of a microorganism according to claim 9 or 10 as a donor organism for genetic material, in particular for inserting a gene encoding a formaldehyde hydrogenase or formaldehyde dismutase and / or the associated promoter sequence into a microorganism or a cell

14 Use of a microorganism according to claim 9 or 10 for obtaining a gene encoding a formaldehyde dehydrogenase or formaldehyde dismutase and / or the associated promoter sequence

15. Biomass obtained by performing the method according to any one of claims 1 to 8.

16. Device for performing the method according to one of claims 1 to 7, characterized in that it contains at least one degradation fermenter and means for regulating the pollutant concentration in the degradation fermenter or fermenters.

17. Device for carrying out the method according to claim 8, characterized in that it comprises a mutation fermenter for the cultivation, mutagenic treatment and stabilization of the microorganism culture, a selection fermenter, means for returning part of the culture from the selection fermenter to the mutation fermenter, agents for regulating the pollutant concentration in the selection fermenter, contains at least one degradation fermenter and means for regulating the pollutant concentration in the degradation fermenter or fermenters.