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  A process for the isolation and acclimatization of bacteria for lignin degradationRelated Patent Categories: Chemistry: Molecular Biology And Microbiology, Micro-organism, Per Se (e.g., Protozoa, Etc.); Compositions Thereof; Proces Of Propagating, Maintaining Or Preserving Micro-organisms Or Compositions Thereof; Process Of Preparing Or Isolating A Composition Containing A Micro-organism; Culture Media Therefor, Bacteria Or Actinomycetales; Media ThereforA process for the isolation and acclimatization of bacteria for lignin degradation description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060121592, A process for the isolation and acclimatization of bacteria for lignin degradation. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE INVENTION [0001] Present invention relates to a novel, aerobic biological process for the degradation of lignin using the defined consortium of ligninolytic bacteria isolated from the specific site. DESCRIPTION OF THE PRIOR ART Fungi [0002] Lignin is the most abundant aromatic polymer in the biosphere. It is found in the cell wall of all vascular plants in association with cellulose and hemicellulose. Because inter-unit bonds in lignin are not hydrolysable, lignin is difficult to degrade either chemically or biologically. Lignin surrounds cellulose in the plant cell wall forming a matrix, which is itself resistant to degradation. Lignin biodegradation is responsible for much of the natural destruction of wood in use, and it may have an important role in plant pathogenesis. On the other hand, potential applications utilizing lignin-degrading organisms and their enzymes have become attractive, because they may provide environmentally friendly technologies for the pulp and paper industry. To date, only a few groups of organisms are capable of degrading complex lignin polymers, and they are best exemplified by the white rot fungi. Most of the research concerning biodegradation of lignin has been centered on some fungi only such as Phanerochaete chrysosporium, Streptomyces viridosporus, Pleurotus eryngii, Trametes trogii, Fusarium proliferatum (Regaldo et al., 1997) etc. (1) [0003] Wood-rotting basidiomycetous fungi that cause white rot in wood are the most efficient lignin degraders in nature (Kirk and Farrell, 1987; Eriksson et al., 1990), and they are perhaps nature's major agents for recycling the carbon of lignified tissues. No other microorganisms as pure culture have been described to mineralize lignified tissues as efficiently (Kirk and Cullen, 1998). They are a group of taxonomically heterogeneous higher fungi, characterized by their unique ability to depolymerize and mineralize lignin using a set of extracellular lignnolytic enzymes. Lignin degradation by white-rot fungi has been intensively studied during the last thirty years in relation to biotechnical applications such as biopulping, biobleaching, treating of pulp mill effluents, and soil bioremediation (Akhtar et al., 1992, 1998; Lamar et al., 1992; Messner and Srebotnik, 1994). [0004] The enzymology and molecular biology of lignin degradation has been mainly studied in Phanerochaete chrysosporium (Gold and Alic, 1993; Cullen, 1997; Kirk and Cullen, 1998). Many of the enzymes necessary for lignin degradation were not characterized before the beginning of the 1980s when virtually only laccase had been known. Since the discovery of two important peroxidases in the beginning of the 1980s, namely lignin peroxidases (LiPs) in 1983 and manganese peroxidases (MnPs) in 1984 (Kirk and Farrell, 1987), an array of enzymes have been isolated from fungi and characterized in detail. [0005] LiP (lignin peroxidase) is believed to be one of the key enzymes in lignin biodegradation by white rot fungi. DNA probes specific for the genes encoding major lignin peroxidases (LiP) isozymes of P. chrysosporium were constructed. These probes were used to study the temporal expression of LiP enzymes in defined low nitrogen medium. (Boominathan et al. 1993). [0006] Aspergilli, the versatile ascomycetes are also found to transform at a rapid rate a wide spectrum of lignin related aromatic compounds. They are shown to overproduce high levels of hemicellulolytic enzymes. (4) [0007] Maria Teresa et al. have shown that Bjerkandera sp. Strain BOS55 is a white rot fungus that can bleach EDTA extracted eucalyptus oxygen delignified Kraft pulp (UKP) without any requirement for manganese. Furthermore, under manganese free conditions, addition of simple physiological organic acids (e.g. Glycolate, glyoxylate, oxalate and others) at 1-5 m stimulated brightness gains and pulp delignification two to three fold compared to results not receiving acids. The stimulation was attributed to increase production of MnP and LiP as well as increased physiological concentrations of veratryl alcohol and oxalate. These factors contributed to greatly improved production of superoxide anion radicals, which may have been accounted for the more extensive biobleaching. (5) [0008] Till now, all the basics and applied research work has centered on fungi only. In case of biobleaching of raw pulp, the application of fungi is not feasible due to its structural hindrance caused by fungal filaments. Therefore, identification of bacteria having lignin oxidizing enzymes would be of significant importance. [0009] Bacteria [0010] The role of bacteria in lignin biodegradation is still a matter of conjecture. Some workers have demonstrated that either mixed (Sundman et al., 1968) or pure culture of bacteria (Sorensen, 1962) can grow on lignin as a carbon source. Pseudomonas spp. was claimed by Kawakami (1976) and Odier and Monties (1977) to degrade plant lignins. Odier and Montis also indicated several other bacterial strains that can use within seven days time more than 50% of the lignin supplied in a mineral medium containing glucose. [0011] Several Nocardia and Pseudomonas spp. as well as some unidentified bacteria, isolated from lake water containing high loads of waste lignin, were tested for their capacity to release .sup.14CO.sub.2 from specifically .sup.14C-labelled dehydropolymer of coniferyl alcohol (DHP) or corn stack lignins. However only some of them could release significant amount S of .sup.14CO.sub.2 from the labeled lignin. The tested Nocardia spp. was more active than the Pseudomonas spp. and the unidentified bacteria.(6) [0012] Actinomycetes are filamentous bacteria which arc found in soil and composts where lignocellulose is decomposed. Several reports provide evidence that several species belonging to the genus Streptomyces are able to degrade lignin. Other lignin degrading Actinomycetes include Thermomonospora mesophila, Actinomadura, Micromonospora with Streptomyces exibiting the highest lignin degrading ability. In most of the studies, the lignin degrading enzyme was produced at higher levels in cultures containing lignocellulose which suggests that an induction mechanism was active. [0013] Ajit Verma et al. (1994) while working on symbiotic relationship between termites and their intestinal microbes concluded that both termite soil and termite gut bacteria play an important role in polymer depolymerization. Gut bacteria have the capacity to degrade cellulosic and hemicellulosic materials more efficiently. Several bacterial isolates which hydrolyze cellulose and hemicellulose have been obtained in pure culture from the termite gut. Some of these are Arthrobacter sp., Bacillus cereus, Clostridium sp., Micrococcus sp., Streptomyces sp., Serratia marcescens. Only a few xylan decomposing bacteria have been obtained from the termite gut (Micrococcus luteuns, Pseudomonas aeruginosa). The question of lignin degradation by termites is intriguing, since much of the termite gut is anaerobic and natural anaerobic mechanisms of lignin degradation are unknown.(7) [0014] Berrocal et al. (1997) have shown that cell free filtrates from streptomyces sp. Grown in solid state fermentation were capable of solubilising up to 20% of the [.sup.14C] lignin. The activity of two enzymes, extracellular peroxidase and phenol oxidase (laccase) was found to correlate with both solubilisation and mineralisation rates of lignin.(8) [0015] The presence of bacteria in rotted wood often in association with fungi has been the subject of numerous reports. However, their exact role in degradation of wood components is still unclear. While the availability of nutrient nitrogen represses metabolism of synthetic .sup.14C lignin to CO.sub.2 by Phanerochaete Chrysosporium, high levels of organic nitrogen were optimal for lignin degradation by the bacterium Streptomyces badius. (9) [0016] Few bacterial isolates which exhibited a remarkable capability of bleaching the hardwood kraft pulp as reported in a previous pending patent application, have shown lignin degradation capability. [0017] Enzymes are the catalytic cornerstones of metabolism, and as such are the focus of intense worldwide research, not only in biological community, but also with process designers/engineers, chemical engineers, and researchers working in other scientific fields. Since ancient times, enzymes have played a central role in many manufacturing process, such as in the production of wine, cheese, bread etc. The latter half of the twentieth century saw an unprecedent expansion in our knowledge of the use of microorganisms, their metabolic products, and enzymes in a broad area of basic research and their potential industrial applications. Only in the past two decades, however have microbial enzymes been used commercially in the Pulp and Paper industry. (10) [0018] The most common application of enzymes in paper industry is to enhance bleaching. At least 15 patents or patent disclosures dealing with enzymatic treatments to enhance bleaching of Kraft pulps were submitted between 1988 and 1993. [0019] Lignin, correctly known as "nature's plastic", although resistant to microbial attack, certain filamentous fungi is capable of degrading it to the level of CO.sub.2. Until 1981, it was not even known whether enzymes are involved in lignin depolymerization. Ming Tien et al. from university of Michigan have discovered enzymes that degrade lignin. [0020] The major enzymes involved in lignin biodegradation by fungi are two extracellular heme containing peroxidases: Lignin Peroxidase (LiP, EC 1.11.1.14) and Manganese Peroxidases (MnP, EC: 1.11.1.13) (Kirk et al., 1987), Gold et al. (1989); Hatakka (1994). The main difference between LiP and MnP is the nature of substrate that is oxidized. LiP is capable of oxidizing non phenolic or phenolic lignin structures directly to yield aryl cation radicals and phenoxy radicals, respectively. (Kirk, 1987). For MnP, the primary reducing substrate is divalent manganese ion Mn.sup.2+. The catalytic cycle of MnP in the presence of appropriate chelators generates highly reactive Mn.sup.3+ chelate complexes that are able to oxidize various phenols and carbon centered radicals, respectively. (Wariishi et al., 1989; Hofrichter et al., 1998). [0021] Usually MnP is not able to oxidize or depolymerize the more recalcitrant non-phenolic lignin structures that make up about 90% of the lignin in wood. Interestingly, it seems that primary attack on lignin requires low molecular weight agents, because LiP and other enzymes are too large to penetrate lignocellulose. (Call et al., 1997). Because of these discrepancies, it has been proposed that there are mechanisms that enable MnP to cleave non-phenolic lignin structures via the action of small mediators such as thiyl or lipid radicals. (Wariishi et al., (1989), Bao et al., (1994)). 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