Chemistry: molecular biology and microbiology – Micro-organism – per se ; compositions thereof; proces of... – Bacteria or actinomycetales; media therefor
Reexamination Certificate
1999-08-23
2001-09-04
Ware, Deborah K. (Department: 1651)
Chemistry: molecular biology and microbiology
Micro-organism, per se ; compositions thereof; proces of...
Bacteria or actinomycetales; media therefor
C210S600000, C210S601000, C435S262500, C435S264000, C435S821000, C435S822000
Reexamination Certificate
active
06284514
ABSTRACT:
The invention relates to the new bacterial strain Aureobacterium sp. K2-17 and to a process for the microbial decontamination of materials polluted with compounds from the production of phenoxyalkanoic acid herbicides, such as 2,4-dichlorophenoxybutyric acid (DCPB), 4-chloro-2-methylphenoxybutyric acid (MCPB), 2,4-dichlorophenoxyacetic acid (2,4-D), 4-chloro-2-methylphenoxyacetic acid (MCPA), 2,4-dichlorophenol (DCP), and 4-chloro-2-methylphenol (MCP) in a pH range of from slightly acidic to strongly alkaline.
The chemical industry production sites where herbicides have been manufactured for decades, as well as the vicinities thereof are contaminated with starting materials, intermediates, and final products of said production. This involves soils, surface waters and ground waters in these areas but also the production plants and buildings themselves. Inter alia, this also implies former production sites of phenoxyalkanoic acid herbicide manufacturing. The compounds present for this reason, such as DCPB, MCPB, 2,4-D, MCPA, DCP, and MCP are known to be toxic, and some of them have cancerogenic and teratogenic effects. The dismantling of chemical plants where these compounds have been manufactured, and the crushing of masonry in shredding plants gives rise to rubble which has to be decontaminated in order to remove these harmful compounds, thereby avoiding health hazards of exposed persons and also protecting flora and fauna.
In addition to contaminated rubble, there are also aqueous waste flows highly polluted with these substances. As a result, the contaminations also reach the soils and ground waters in the vicinity of such (former) sites. The disposal of waters from the production of such compounds therefore requires special concern because they contain these harmful components in a concentrated form. Namely, it has been found that introducing these production waters into industrial clarification plants may give rise to significant interference of the biological equilibrium and thus, the performance of these plants, affecting the rate and degree of degradation. An effective solution of the contamination problem requires special conditions and implies various preconditions.
Various processes on a physical-chemical basis are known for the decontamination of solid matrices such as rubble. Thus, while thermal processes are effective, their disadvantage lies in their high cost. In addition, extraction or washing processes with subsequent absorptive removal of pollutants—even in the event of polluted waters—for decontaminating solid matrices are well-known. However, they merely transfer the problem to another carrier, although sometimes in a highly concentrated form, and consequently give rise to the above-mentioned drawbacks as well.
Owing to the vast metabolic potential of microorganisms, decontamination processes on a microbial basis are preferred. Thus, microbial methods generally are effective and low-cost variants wherein organic compounds undergo degradation to produce biomass, water, carbon dioxide, and heat. To this end, indigenous microorganisms adapted to the corresponding medium can be employed. By optimizing the conditions, the metabolic potential can be utilized to full extent As a result of growth, the biocatalytic potential is even increased in a quasi autocatalytic fashion. However, it is also possible to add ex situ cultivated microorganisms (species or consortia) as starting cultures to contaminated materials where redevelopment may be conducted in most various processing regimes (i.e., in situ, on site, off site, reactors, pits, and the like). With polluted and concentrated waters, separate treatment and degradation in reactors could be performed.
The actual sites, i.e., the waters and ground waters, as well as soils, may also be subjected to microbial treatment, be it for plants during running production or those sites which, following discontinuation of production and dismantling of plants, are to be recultivated or put to new utilization. It is disadvantageous that the pH values of these sites range from slightly acidic to alkaline. Aqueous eluates from concrete demolition are even strongly alkaline, correspondingly restricting the variety of the microorganism species and posing special preconditions on decontamination on a microbial basis.
The productive decontamination of chlorinated and methylated phenols and phenoxyalkanoic acids in the neutral pH range using single cultures (Pieper, D. H. et al., Arch. Microbiol. 150 (1988) 95; Horvath, M. et al., Appl. Microbiol. Biotechnol. 33 (1990) 213; Kilpi, S., Microbiol. Ecol. 6 (1980) 261; Short, K. A. et al., Can. J. Microbiol. 36 (1990) 822; Tiedje, J. M. et al., J. Agr. Food Chem. 17 (1969) 1021) and consortia (Bloedorn, I., Ph.D. Thesis 1990, Halle University; Haugland, R. A. et al., Appl. Env. Microbiol. 56 (1990) 1357; Lappin, H. M., Appl. Env. Microbiol. 49 (1985) 429; Oh, K. H. and Tuovinen, O. H., J. Ind. Microbiol. 6 (1990) 275) is well-known. The degradation of 2,4-dichlorophenol and 4-chloro-2-methylphenol by a Gram-negative bacterium, strain S1, has been described by Lechner et al. (Biodegradation 6, 1995, 83).
As has been set forth, there is an additional complication in that these contaminations occur in strongly alkaline media. This is the medium of the so-called alkaliphiles (K. Horikoshi: “Microorganisms in Alkaline Environments”, VCH Weinheim, New York, 1991). Recently, it has been demonstrated that microorganisms concentrated from such contaminated masonry are capable as consortia of completely degrading various phenoxyalkanoic acid derivatives in aqueous eluates having pH values of up to 12.5 (Müller et al., DE 44 24 756.7).
Likewise, corresponding alkaliphilic pure cultures are known which are capable of degrading phenoxyacetic acid derivatives (Hoffmann et al., Acta Biotechnol. 16 (1996) 121; Maltseva et al., Microbiology 142 (1996) 1115; Müller et al., 1st Internat. Symp. Extremophiles, Estoril, 1996, Portugal, p. 208). Compared to consortia, however, monocultures are restricted in their metabolic spectrum. Indeed, they have the advantage of easier handling, but contaminations from herbicide production frequently contain a spectrum of phenoxyalkanoic acid derivatives. To date, no microorganisms are known that would be capable of degrading phenoxybutyric acid herbicides such as DCPB/MCPB in an alkaline medium as well.
SUMMARY OF THE INVENTION
Therefore, it was the basic object of the invention to develop a practicable and cost-effective process for the microbial decontamination of material polluted with compounds from the phenoxyalkanoic acid herbicide production, find and combine strains of microorganisms suitable for complete degradation of said compounds. In particular, these microorganisms should be usable in the microbial decontamination of, inter alia, eluates from demolition materials of buildings and plants, or from waste waters and ground waters.
A new bacterial strain has been found which is excellently suited for use in the degradation of DCPB and/or MCPB in a range of from slightly acidic to alkaline. It is the strain Aureobacterium sp. K2-17. It has been deposited with the Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH under the number DSMZ 11288 on Nov. 18, 1996.
Said strain grows in a range of from neutral to alkaline and, surprisingly, is capable of cleaving DCPB and MCPB to form the corresponding phenol derivatives and C
4
derivatives.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Aureobacterium sp. K2-17 is cultivated according to per se usual methods in a continuous or discontinuous fashion, or by using other strategies of feeding, e.g., either on a complex medium containing yeast extract and/or peptone, where a pH value of from 7 to 9.5 may be pre-adjusted, or using n-alkanoic acids (acetate, butyrate), dicarboxylic acids (succinate), or other suitable carbon/energy sources. Following addition of the phenoxybutyric acids, these compounds are degraded without a substantial delay.
In a preferred embodiment of the invention, said new strain, Aureobacterium sp. K2
Babel Wolfgang
Muller Roland
Norris McLaughlin & Marcus P.A.
UFZ-Umweltforschungszentrum Leipzig-Halle GmbH
Ware Deborah K.
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