DE20207502U1 - Photoprotected starter culture for microbiological treatment of water, soil, sediments and/or sludges, comprises live chemolithoautotrophic bacteria immobilized in a matrix coated with pigments and/or adsorbents - Google Patents

Abstract

A starter culture for microbiological treatment of water, soil, sediments and/or sludges, comprising live chemolithoautotrophic bacteria immobilized in a matrix coated with pigments and/or adsorbents, is new.

Description

Soll Holding GmbH, Kronberg

13.05.2002

"Microbiological culture for the initiation of microbiological processes in water.

Soils sediments and/or sludges "

The present invention relates to a microbiological culture for the initiation of microbiological processes in waters, soils, sediments and/or sludges using living chemolithoautotrophic bacteria, wherein the bacteria are immobilized in a matrix.

Standing and flowing natural waters generally have a certain self-cleaning power, ie they can break down contaminants to a limited extent. These self-cleaning powers are often not sufficient for heavily polluted waters. Microorganisms are often added to these waters to support the (self-)cleaning process. These microorganisms can break down harmful nitrogen compounds into harmless compounds such as elemental nitrogen.
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The added microorganisms serve to initiate, support or take over the self-cleaning powers present in natural waters and aquatic systems.

The microorganisms can be used in the form of cell suspensions and introduced into the water in this form, if necessary with an aqueous solvent. The use of powdered microorganisms is also possible. In these preparations, the microorganisms are first converted into so-called permanent forms, such as spores, or lyophilized. Due to the water's own current and diffusion, the microorganisms do not stay in one place but also reach other regions of the water. In these regions, the living conditions for the microorganisms can be unfavorable, so that pollutants cannot be removed. Furthermore, it is not possible to fix the microorganisms in particularly polluted water regions.

In the area of aquariums, problems arise even with small amounts of soluble nitrogen compounds, as ammonia, for example, has a toxic effect on fish at a concentration of just 0.01 mg/L. In aquariums, which are artificial systems in particular, the self-cleaning process is particularly susceptible to disruption even with small amounts of foreign substances, such as nitrogen compounds, etc.

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Especially if there are hardly any active microorganisms in the water to be treated, active microorganisms must be added in sufficiently high active concentrations in order to

-5 to activate the self-cleaning powers of the water. For operators of garden ponds and smaller bodies of water, microorganisms that are used to improve water quality are usually available in so-called permanent forms or lyophilized. For larger bodies of water, the use of cell suspensions is recommended. It is also known to use the microorganisms in encapsulated form.

The cell suspensions known from the state of the art and also the microcapsules that contain microorganisms do not generally use chemoautotrophic microorganisms in defined species communities. They also have the disadvantage that the preparations are only stable for a very short period of time and the microorganisms die after just one or two days. Such preparations are therefore not suitable for commercial use.

If microorganisms are to be used to inoculate water bodies in order to activate their self-cleaning powers, the microorganisms used must be present in very high concentrations.

When it comes to stabilizing the nitrogen cycle, microbiological processes such as nitrogen fixation, nitrogen assimilation and denitrification usually do not cause any problems; the degradation performance from nitrification processes and also the mineralization of organic nitrogen compounds are often insufficient.

The disadvantage of many microbiological processes is that the activity period of the microorganisms is only a few days and then they die. In addition, many microorganisms do not form spores and cannot be converted into permanent forms; for example, they can only be lyophilized with a loss of activity. These microorganisms must be used in vegetative form, which in turn means that they must be stored under conservation conditions.

WO 02/24583 A1 discloses a microbiological culture for the initiation of microbiological processes in water, soil, sediment and/or sludge, in which living chemolithoautotrophic bacteria are used. The bacteria used are immobilized in a matrix, whereby this matrix usually consists of a polymer framework.

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The microbiological culture known from the state of the art is well suited as a starter culture for microbiological processes in water and soil. However, it has the disadvantage that its activity can be impaired by strong light radiation. This is particularly the case when the microbiological culture is used in shallow, clear water ^ 5 where sunlight can develop its full power.

The object of the present invention was to provide microbiological starter cultures which are suitable for starting microbiological processes in an aquatic system and thus initiating the self-cleaning power of this system.

The present invention accordingly relates to a microbiological culture for the initiation of microbiological processes in water, soil, sediments and/or sludge using living chemolithoautotrophic bacteria, wherein the bacteria are immobilized in a matrix, characterized in that the matrix comprises pigment and/or adsorbent or is coated therewith.

In the context of the present invention, immobilized means that the bacteria, hereinafter also referred to as microorganisms, are not used as such in the form of a cell suspension or solution, but that they are surrounded by and/or applied to a matrix material, whereby the preservation conditions are maintained. The immobilized bacteria are hereinafter also referred to as immobilizates.

The pigment and/or adsorbent contained according to the invention can be present within the matrix, mixed with the matrix material or, if the matrix surrounds the microorganisms, also applied to the matrix material in the form of a "coating".

Surprisingly, it was found that the bacterial cultures according to the invention in immobilized form are well suited to starting microbiological processes in water and soil, and that the cleaning processes in these systems can thus be significantly accelerated. The pigments and/or adsorbents used according to the invention also protect the bacterial cultures from excessive light during use, so that they can develop their activity at their place of use over a much longer period of time compared to the cultures from the state of the art. The matrix material also shows greater stability. Moisture or water from the system to be cleaned come into contact with the microorganisms, and thus contact also takes place between the harmful substances and the microorganisms, breaking down these substances. The

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The starter culture according to the invention is particularly suitable for the degradation of organic and inorganic nitrogen compounds.

The waters and soils in which the bacterial cultures according to the invention can be used include all water- or moisture-containing systems. Waters in the sense of the present invention are natural and artificial standing and flowing bodies of water, such as ponds and lakes, sewage systems, aquariums, water from water circuits of industrial plants and household systems, etc. Soils include the earth as subsoil on land and in water, but also sediments and sludges, whereby the transition between waters and sediments is fluid depending on the water content.

The bacterial cultures according to the invention are particularly suitable for improving the cleaning performance of aquatic systems such as aquariums, ponds, lakes and sewage treatment plants.
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The pigments and/or the UV radiation filters can, for example, be immobilized together with the microorganisms and be present in the core or incorporated into the capsule wall. This embodiment also includes the fact that these components are present both in the interior of the capsule in the matrix and in the capsule wall.

Any inorganic or organic pigments/adsorbents that do not have a negative effect on the activity of the microorganisms can be used as pigments and/or adsorbents. Examples of inorganic pigments are carbon black, lime (CaCO ₃ ), titanium dioxide, lead white, zinc white, lithopone, antimony white, iron oxide black, manganese black, cobalt black, antimony black, lead chromate, red lead, zinc yellow, zinc green, cadmium red, cobalt blue, Prussian blue, ultramarine blue, manganese violet, cadmium yellow, Schweinfurt green, molybdate orange and molybdate red, chrome orange and chrome red, chrome oxide green, strontium yellow and/or naturally occurring pigments such as ochre, umber, green earth, terra di siena, graphite, etc. A suitable adsorbent is, for example, activated carbon. Dark pigments and/or adsorbents such as carbon black or activated carbon are particularly preferred. Activated carbon, for example, acts as a pigment and protects the starter culture according to the invention from undesirable light influences, while at the same time it is able to bind the undesirable substances such as NH ₄ ⁺ formed by microorganisms during the degradation process. Furthermore, components such as activated carbon and soot have the advantage that they additionally stabilize the matrix material and thus protect it from premature decay or decomposition.

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The microorganisms are preferably immobilized in a matrix, whereby capsules, gels and/or gel beads have proven to be particularly suitable as matrix forms. This type of immobilization has the advantage that moisture or water from the system to be cleaned can be

-5 star can penetrate into the immobilized material via a network structure or diffusion present in the capsule or gel materials and thus come into contact with the microorganisms. At the same time, microorganisms are also released into the environment via the capsule wall or gel, which is preferably permeable to water and/or microorganisms, so that contact can take place outside the capsules between the harmful substances and the microorganisms, breaking down these substances.

The capsules or spheres preferably used preferably have a diameter of about 100 to about 10,000 pm, in particular from 100 to 5,000 pm, in which the microorganisms in solid or liquid form are surrounded by, permeated by and/or applied to a solid to gel-like, usually polymeric, preferably porous polymer material.

By selecting the materials for the capsules/spheres, such as natural or synthetic polymers, the capsule/sphere can be designed in such a way that the bacteria and the substrate to be cleaned (water) can come into contact. Any existing capsule wall can be made tight, permeable or semi-permeable. The material of the capsules/spheres can also be made up of several layers, i.e. one or more materials can be used. This opens up a wealth of possibilities for releasing the immobilized substance in a controlled manner, e.g. by destroying the shell or by permeation or by chemical reactions that can take place inside the microcapsules.

In a preferred embodiment of the present invention, the capsule wall is permeable to water and the substances dissolved therein. In this embodiment, the harmful substances come into contact with the microorganisms in such a way that the water penetrates the surface into the balls and the cleaning processes take place inside. The cleaning process causes the microorganisms to multiply until the capacity limit of the capsule/ball or gel is reached and the wall breaks open, i.e. the microorganisms are released.

Natural or synthetic polymers can be used as matrix materials to produce the immobilized microorganisms.

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In a preferred embodiment, gel-forming polymers and/or polymers suitable for producing the preferred forms such as capsules, spheres and/or gels are used. These have the advantage that bacteria can be absorbed or stored within the gel structure. Preferably, however, the materials should have such strength and abrasion resistance that the immobilized microorganisms can be stored in this form under so-called maintenance conditions, i.e. with the addition of substrate and oxygen.

In a preferred embodiment, materials are used which dissolve or degrade slowly in water, preferably at a defined rate, so that the microorganisms are slowly released over a defined period of time.

Also preferred are polymers that can optionally also serve as a carbon source for the microorganisms used. In this embodiment, the matrix is broken down and decomposed by the microorganisms. As soon as the structure has sufficiently large pores, the microorganisms are released.

Examples of suitable polymers are polymeric polysaccharides such as agarose or cellulose, proteins such as gelatin, gum arabic, albumin or fibrinogen, ethylcellulose, methylcellulose, carboxymethylethylcellulose, cellulose acetates, alkali cellulose sulfate polyanil-Nn, polypyrrole, polyvinylpyrolidone, polystyrene, polyvinyl chloride, polyvinyl alcohol, polyethylene, polypropylene, copolymers of polystyrene and maleic anhydride, epoxy resins, polyethyleneimines, copolymers of styrene and methyl methacrylate, polystyrenesulfonate, polyacrylates and polymethacrylates, polycarbonates, polyesters, silicones, methylcellulose, mixtures of gelatin and water glass, gelatin and polyphosphate, cellulose acetate and phthalate, gelatin and copolymers of maleic anhydride and methyl vinyl ether, cellulose acetate butyrate, chitosan, polydialkyldimethylammonium chloride, mixtures of polyacrylic acids and Polydiallyldimethylammonium chloride and any mixtures of the foregoing.

The polymer material may optionally be cross-linked. Common cross-linkers are glutaraldehyde, urea/formaldehyde resins, tannic compounds such as tanic acid, alkaline earth ions such as Ca ²⁺ ions, which can be added as chlorides, for example, and mixtures thereof.
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In a particularly preferred embodiment, alginates and alginate derivatives are used as matrix material. The alginates have the advantage that they have no negative influence

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on the activity of microorganisms, and they can be slowly broken down by microorganisms over a certain period of time, from one week to several months. Due to the slow degradation of the matrix, the enclosed microorganisms are gradually released to a greater extent. From the biodegradability

♦ 5 The high quality of the wall material results in the additional advantage that no residues or waste products remain in the water. If the immobilized bacterial cultures are e.g.

^v B. in a suitable container or a device for their reception and storage in the medium to be treated, e.g. in a filter, this can be refilled with the microorganisms according to the invention after the immobilized microorganisms used have dissolved.

If the matrix material is in the form of a capsule or sphere, the wall has a multilayer structure in a further preferred embodiment, whereby gel-forming polymers and non-gel-forming, preferably film-forming polymers can be combined for the outer wall. In a preferred embodiment, alginates or alginate derivatives are used as gel-forming materials and polymers selected from cellulose derivatives, in particular sodium cellulose sulfate, polydialkyldimethylammonium chlorides and/or polyethyleneimines, are used as further, preferably film-forming materials. The polymer materials used in addition to the alginate or the alginate derivatives preferably form the outer capsule wall. It has been found that the use of an outer capsule material selected from the above-mentioned polymers can significantly improve the abrasion resistance of the microcapsules and thus the storage life.

In a particularly preferred embodiment, purified alginates, in particular the alginates described under CAS numbers 9005-38-3 and 9005-32-7, are used as gel-forming materials. The purified alginates have the advantage that they contain only small amounts of free organic substances, which may impair the stability and activity of the microorganisms. The alginates used preferably have a high proportion of L-guluronic acid units.

In a further preferred embodiment, layered and framework silicates, particularly preferably zeolites, are added to the alginate. With their lattice structures, the silicates stabilize the gel material and slow down the decomposition process of the alginate while simultaneously adsorbing ammonium and calcium onto the mineral component of the spherical matrix.

•i :

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The zeolites used consist of more than 70% clinoptilolite with inert admixture minerals such as quartz. The grain size of the mineral admixtures is less than 600 pm. The admixture amounts to 0.5 to 50 percent by mass of the alginate dry mass used. Preferably, 5-30% w minerals are used, particularly preferably w (zeolite) = 15-30% to 70 - 85% alginate.

Any microorganism suitable for water treatment can be used as microorganisms, including marine microorganisms, algae and fungi. Preferably, the microorganisms are selected from chemolithoautotrophic nitrifiers, such as ammonia oxidants and nitrite oxidants, which can be selected from nitrifying microorganisms, in particular bacteria of the genera Nitrosomonas, Nitrosococcus, Nitrosospira, Nitrosovibrio and Nitrosospira, in particular the species Nitrosomonas halophila, Nitrosomonas eutropha and Nitrosomonas europaea, Nitrosomonas oligotropha, Nitrosomonas ureae, Nitrosomonas aestuarii, Nitrosomonas marina, Nitrosomonas sp. 3 Nm 51, Nitrosomonas communis, Nitrosomonas nitrosa, Nitrosomonas sp. 1 Nm 33, Nitrosomonas sp. 2 Nm 41, Nitrosomonas cryotolerans, as well as the nitrite oxidizing bacteria of the genera Nitrobacter and Nitrospira, in particular Nitrobacter winogradskyi.

Heterotrophic nitrifying bacteria are also suitable, such as fungi of the genus Aspergillus, Penicillium and Cephalosporium, algae, Arthrobacter sp., Alcaligenes faecalis, Nocordia sp. and heterotrophic denitrifying bacteria such as Paracocus sp., in particular Paraccocus pantothrophas, and Pseudomonas sp. Any combination, ie mixed cultures, of microorganisms can also be used. By using mixed cultures, synergistic effects can be achieved in terms of activity and degradation performance. Examples of mixed cultures are, for example, combinations of the species Nitrosomonas and Nitrobacter and, if necessary, heterotrophic microorganisms.

In a particularly preferred embodiment, species communities of different bacteria are used for cleaning and processing water, soil, etc., such as for breaking down organic and inorganic nitrogen compounds. The species used can first be grown in pure culture according to their specific cultivation conditions and then immobilized. Cultivating the bacteria in pure culture makes it possible to put together almost any species community in almost any species ratio. An example of a particularly preferred species community in the immobilizate consists of a) ammonia-oxidizing (e.g. Nitrosomonas) and b) nitrite-oxidizing (e.g. Nitrobacter) and possibly c) nitrate and nitrite-reducing bacteria (e.g. Paracoccus).

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It has proven to be preferred if the species ratio of the cell numbers in the immobilizate is preferably in the range of a:b 1:10,000 to 1:1 and particularly preferably from 1:1000 to 1:10 and the species ratio of b:c is preferably between 1000:1 to 1:1 and particularly preferably between 100:1 to 5:1.
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Depending on the intended use, the specialist can determine the appropriate types and their relationship to one another based on his or her specialist knowledge and, if necessary, after carrying out tests or using computer simulations.

In order to be able to start a system microbiologically in a short time, it has proven useful to add the starter cultures in a sufficiently high concentration.

To produce the immobilized bacteria according to the invention, cell suspensions are usually first grown in pure culture at a concentration of 1 x 10 ⁶ to 5 x 10 ⁹ cells/ml. In order to obtain microorganisms in the highest possible concentration in the microcapsule, the cell suspensions obtained are then preferably concentrated to 5 x 10 ⁸ to 6 x 10 ⁹ cells/ml. Concentration can be carried out using conventional filtration methods known from the prior art.

In particular when nitrifying microorganisms are immobilized, it has proven particularly suitable to use the microorganisms in the form of aqueous cell suspensions. In a particularly preferred embodiment, stabilized microorganisms are used, in particular those grown and stabilized according to the method described in German patent application 199 08 109.3-41 by adding NO and/or NO ₂ .

A particularly good stabilization of the microorganisms can be achieved if they are used as a cell suspension containing a buffer system. Examples of suitable buffers are acetic acid/acetate, HCO ₃ VCO ₃ ² ", phosphoric acid/H ₂ PO ₃ 7HPO ₃ ² ", citric acid/citrate, lactic acid/lactate, solid CaCO ₃ , etc.

In order to achieve optimum activity of the microorganisms, the pH value in the gel capsules is preferably between 4 and 9, particularly preferably between 5 and 8 and in particular between 6.5 and 8.5. If adjustable under the application conditions, the starter cultures according to the invention are preferably carried out in a temperature range of 8 ⁰ C to 35 ° C, particularly preferably in a range of 15 ° C to 30 ⁰ C and in particular between 20 ⁰ C and 30 ° C.

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The microcapsules can be produced in a conventional manner by encapsulating cell suspensions or solutions.

^5 The pigments and/or adsorbents contained in the invention can be mixed with the starting materials during production or they can be applied to the finished cultures after completion of the production process.

If microcapsules containing several different microorganisms are to be produced, the cell suspensions/solutions are mixed together in the desired proportions as soon as the desired cell concentration has been achieved and then immobilized in a manner known per se. Suitable methods for immobilizing the microorganisms are the microencapsulation methods known from the state of the art.

Examples of possible manufacturing processes are phase separation processes, also called coacervation, mechanical-physical processes, interfacial polymerization and adsorptive processes.

Coacervation means that a dissolved polymer is converted into a polymer-rich phase that still contains solvent by means of desolvation. The coacervate attaches itself to the interface of the material to be encapsulated, forming a coherent capsule wall and is solidified by drying or polymerization.

Mechanical-physical processes are also suitable for coating solid core materials, in which the coating is carried out in a fluidized bed or by spray drying.

In the above-mentioned interfacial polymerization processes, wall formation occurs by polycondensation or polyaddition from monomeric or oligomeric starting materials at the interface of a water/oil emulsion.
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In the adsorptive processes, layers of polyanionic and polycationic polymers are applied to form the capsule wall, which can usually consist of 2 to 20 layers.

The polymers used are preferably used in the form of their solutions, suspensions or emulsions. Aqueous solutions, suspensions or emulsions with a concentration of 0.5 to 10 wt.% have proven to be suitable for microencapsulation.

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As already stated at the beginning, one aspect of the application is to immobilize vegetative microorganisms in such a way that they can be stored for a long period of time under their preservation conditions. In order to maintain the viability of the microorganisms, i.e. their activity, it is therefore particularly preferred if the

a5 Cultivation, concentration if necessary and subsequent immobilisation shall be carried out under gentle conditions, in particular under conservation conditions.

^v den. In order to set the conservation conditions, it is therefore preferable to supply the microorganisms with substrate and oxygen during the processing. In order to obtain a functional product as an end product, which is usually made available to the end user, it is particularly desirable if the conservation conditions mentioned can be maintained without interruption, or at least almost without interruption, during the manufacturing process and also during distribution to the end user.

To produce microcapsules from alginate, a 1 to 5%, in particular 1.5 to 2.5%, alginate suspension is preferably used. This alginate suspension is mixed with a suspension of the microorganisms, which preferably has the highest possible concentration, and then subjected to immobilization in a manner known per se.

The immobilizates produced can be used without further processing steps such as drying. It is also possible to dry the immobilizates obtained for storage purposes. They can be used in the water to be cleaned and/or processed in a conventional manner. Preferably, however, the capsules are placed in a container that can be permanently installed in the water to be cleaned. It is also possible for the immobilizates to be fixed solely due to their specific weight, i.e. not to be carried further by the current.

In a particularly preferred embodiment, the immobilizates obtained are introduced into a filter and fixed by the surrounding filter material.

When used in a body of water that is to be cleaned, the water flows through the filter unit and comes into contact with the immobilized material. The preferably net-like structure of the matrix material allows the water to be cleaned, including the harmful substances, to penetrate into the interior of the immobilized material. The reaction of the immobilized microorganisms with the harmful substances causes them to be broken down. These substances, which are harmful to the water, also act as a nutrient medium for the microorganisms.

• t · ν · * &iacgr;»;

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Before their use according to the invention, the immobilized microorganisms are preferably stored in a ventilated and possibly cooled container in order to minimize any possible loss of activity. In a preferred embodiment, this container is designed as a so-called dispenser from which the immobilized products can be taken in the desired amount.

Claims (14)

1. Microbiological culture for the initiation of microbiological processes in water, soil, sediments and/or sludges using living chemolithoautotrophic bacteria, wherein the bacteria are immobilized in a matrix, characterized in that the matrix comprises or is coated with pigment and/or adsorbent. 2. Microbiological culture according to claim 1, characterized in that pigments and/or adsorbents are selected from activated carbon, soot, lime (CaCO ₃ ), titanium dioxide, lead white, zinc white, lithopone, antimony white, iron oxide black, manganese black, cobalt black, antimony black, lead chromate, red lead, zinc yellow, zinc green, cadmium red, cobalt blue, Prussian blue, ultramarine blue, manganese violet, cadmium yellow, Schweinfurt green, molybdate orange and molybdate red, chrome orange and chrome red, chrome oxide green, strontium yellow and/or naturally occurring pigments such as ochre, umber, green earth, terra di siena, graphite, etc. 3. Microbiological culture according to claim 1 or 2, characterized in that the matrix has the form of capsules, gels and/or gel beads. 4. Microbiological culture according to claim 1 or 2, characterized in that the matrix has a particle diameter of 1 µm to about 10,000 µm, in particular from 100 to 5,000 µm. 5. Microbiological culture according to one of claims 1 to 3, characterized in that the matrix material is selected from natural and/or synthetic polymers. 6. Microbiological culture according to claim 4, characterized in that the polymers are selected from polymeric polysaccharides, such as agarose or cellulose, proteins, such as gelatin, gum arabic, albumin or fibrinogen, ethylcellulose, methylcellulose, carboxymethylethylcellulose, cellulose acetates, alkali cellulose sulfate, polyanillin, polypyrrole, polyvinylpyrolidone, polystyrene, polyvinyl chloride, polyvinyl alcohol, polyethylene, polypropylene, copolymers of polystyrene and maleic anhydride, epoxy resins, polyethyleneimines, copolymers of styrene and methyl methacrylate, polystyrenesulfonate, polyacrylates and polymethacrylates, polycarbonates, polyesters, silicones, methylcellulose, mixtures of gelatin and water glass, gelatin and polyphosphate, cellulose acetate and phthalate, gelatin and copolymers of maleic anhydride and methyl vinyl ether, cellulose acetate butyrate, chitosan, Polydialkyldimethylammonium chloride, mixtures of polyacrylic acids and polydiallyldimethylammonium chloride and any mixtures of the foregoing. 7. Microbiological culture according to one of claims 1 to 5, characterized in that the matrix has a multilayer structure. 8. Microbiological culture according to claim 6, characterized in that a matrix material is selected from gel-forming polymers, in particular from alginates and/or alginate derivatives and a further material is selected from film-forming polymers, in particular from alkali cellulose sulfate, polyethyleneimines and/or polydialkyldimethylammonium chlorides. 9. Microbiological starter culture according to one of claims 1 to 6, characterized in that layered and framework silicates, preferably zeolites, are added to the matrix material. 10. Microbiological starter culture according to one of claims 1 to 8, characterized in that the microorganisms are selected from chemolithoautotrophic nitrifiers, such as ammonia oxidants and nitrite oxidants, such as bacteria of the genera Nitrosomonas, Nitrosococcus, Nitrosospira, Nitrosovibrio and Nitrosospira, in particular the species Nitrosomonas halophila, Nitrosomonas eutropha and Nitrosomonas europaea, Nitrosomonas oligotropha, Nitrosomonas ureae, Nitrosomonas aestuarii, Nitrosomonas marina, Nitrosomonas sp. 3 Nm 51, Nitrosomonas communis, Nitrosomonas nitrosa, Nitrosomonas sp. 1 Nm 33, Nitrosomonas sp. 2 Nm 41, Nitrosomonas cryotolerans, Nitrobacter and Nitrospira, in particular Nitrobacter winogradskyi, heterotrophic nitrifying bacteria such as fungi of the genera Aspergillus, Penicillium and Cephalosporium, algae, Arthrobacter sp., Alcaligenes faecalis, Nocordia sp., heterotrophic denitrifying bacteria such as Paracocus sp. and Pseudomonas sp. and any mixtures of the foregoing. 11. Microbiological culture according to one of claims 1 to 9, characterized in that the bacteria are immobilized in the form of cell suspensions, the concentration of the cell suspensions being between 5 × 10 ⁸ to 6 × 10 ⁹ cells/ml. 12. Microbiological culture according to one of claims 1 to 10, characterized in that a battery mixture consisting of a) ammonia-oxidizing and b) nitrite-oxidizing and optionally c) nitrate- and nitrite-reducing bacteria is used. 13. Microbiological culture according to claim 11, characterized in that the species ratio of the cell numbers in the immobilizate of a:b is in the range from 1:10,000 to 1:1, preferably from 1:1,000 to 1:10 and the species ratio of b:c is preferably between 1000:1 to 1:1 and preferably between 100:1 to 5:1. 14. Microbiological culture according to one of claims 1 to 12, characterized in that the matrix contains a buffer system selected from acetic acid/acetate, HCO ₃ ^- /CO ₃ ^2- , phosphoric acid/H ₂ PO ₃ ^- /HPO ₃ ^2- , HSO ₄ ^- /SO ₄ ^2- , citric acid/citrate, lactic acid/lactate, solid CaCO ₃ .