Microbial biodegradation

About: Microbial biodegradation is a research topic. Over the lifetime, 1647 publications have been published within this topic receiving 75473 citations.

Microbial degradation of pesticide: A review

Abstract: Excessive use of pesticides has been known to be hazardous to the environment, affect soil fertility as well may impart toxicity in living beings. Presently there have been physical, chemical, biological and enzymatic approaches implicated to reduce pesticides. Although aimed to eradicate, physical and chemical methods are inefficient. Curiously, microbial pesticide remediation has been cost effective and thermodynamically more affordable, which may use any physical mater soiled with pesticide. Under favourable conditions microbes have been reported to use pesticides as source of carbon, sulphur and electron donor. Microbes; bacteria, actinomycetes and fungi have been found to help remove or detoxify chlorinated pesticides; polychlorinated diphenyl, polycyclic aromatic hydrocarbons, organophosphorus. Major bacterial genera includes; Bacillus, Pseudomonas, Flavobacterium, Moraxalla, Acinetobacter, Arthrobacter, Paracoccus, Aerobacter, Alkaligens, Burkholderia and Sphingomonas. Fungi with pesticide degradation potential includes;Fusarium, Aspergilus niger, Penicillium, Lentinulaedodes, Lecanicillium, Oxysporum. Among the Actinomycetes theStreptomycetes have been found to successfully detoxify pesticides. Persistent organic pollutants in the form of pesticides have also been reported to be taken care by the microbial enzymes viz-a-viz; dehydrogenase, ligninase, oxygenase, peroxidises, phosphotriesterase, hydrolases, dehalogenase, laccase and organophosphorus acid anhydrolase. Microbial strategies and tools; enzymes and genes involved in pesticide catabolism are reviewed. Key words: Chlorinated pesticides, organophosphors pesticides, bacteria, fungi, enzyme.

Microbial degradation of organophosphorus xenobiotics: metabolic pathways and molecular basis

Abstract: Organophosphorus (OP) xenobiotics are used worldwide as pesticides and petroleum additives. OP compounds share the major portion of the pesticide market globally. Owing to large-scale use of OP compounds, contaminations of soil and water systems have been reported from all parts of the world. OP compounds possess very high mammalian toxicity and therefore early detection and subsequent decontamination and detoxification of the polluted environment is essential. Additionally, about 200,000 tons of extremely toxic OP chemical warfare agents are required to be destroyed by 2007 under Chemical Warfare Convention (1993). Chemical and physical methods of decontamination are not only expensive and time-consuming, but also in most cases they do not provide a complete solution. These approaches convert compounds from toxic into less toxic states, which in some cases can accumulate in the environment and still be toxic to a range of organisms. Bioremediation provides a suitable way to remove contaminants from the environment as, in most of the cases, OP compounds are totally mineralized by the microorganisms. Most OP compounds are degraded by microorganisms in the environment as a source of phosphorus or carbon or both. Several soil bacteria have been isolated and characterized, which can degrade OP compounds in laboratory cultures and in the field. The biochemical and genetic basis of microbial degradation has received considerable attention. Several genes/enzymes, which provide microorganisms with the ability to degrade OP compounds, have been identified and characterized. Some of these genes and enzymes have been engineered for better efficacy. Bacteria capable of complete mineralization are constructed by transferring the complete degradation pathway for specific compounds to one bacterium. In the present article, we review microbial degradation and metabolic pathways for some OP compounds. The biochemical and molecular basis of OP degradation by microbes and the evolution and distribution of genes/enzymes are also reviewed. This article also examines applications and future use of OP-degrading microbes and enzymes for bioremediation, treatment of OP poisoning, and as biosensors.

Biodegradation of individual and multiple chlorinated aliphatic hydrocarbons by methane-oxidizing cultures.

Abstract: The microbial degradation of chlorinated and nonchlorinated methanes, ethanes, and ethanes by a mixed methane-oxidizing culture grown under chemostat and batch conditions is evaluated and compared with that by two pure methanotrophic strains: CAC1 (isolated from the mixed culture) and Methylosinus trichosporium OB3b. With the exception of 1,1-dichloroethylene, the transformation capacity (Tc) for each chlorinated aliphatic hydrocarbon was generally found to be in inverse proportion to its chlorine content within each aliphatic group (i.e., methanes, ethanes, and ethenes), whereas similar trends were not observed for degradation rate constants. Tc trends were similar for all methane-oxidizing cultures tested. None of the cultures were able to degrade the fully chlorinated aliphatics such as perchloroethylene and carbon tetrachloride. Of the four cultures tested, the chemostat-grown mixed culture exhibited the highest Tc for trichloroethylene, cis-1,2-dichloroethylene, tetrachloroethane, 1,1,1-trichloroethane, and 1,2-dichloroethane, whereas the pure batch-grown OB3b culture exhibited the highest Tc for all other compounds tested. The product toxicity of chlorinated aliphatic hydrocarbons in a mixture containing multiple compounds was cumulative and predictable when using parameters measured from the degradation of individual compounds. The Tc for each chlorinated aliphatic hydrocarbon in a mixture (Tcmix) and the total Tc for the mixture (sigma Tcmix) are functions of the individual Tc, the initial substrate concentration (S0), and the first-order rate constant (k/Ks) of each compound in the mixture, indicating the importance of identifying the properties and compositions of all potentially degradable compounds in a contaminant mixture.

Microbial degradation of polychlorinated biphenyls

Abstract: A process for the microbial degradation of polychlorinated biphenyls (PCBs) which comprises treating the PCBs with certain non-pathogenic, hydrocarbon-utilizing strains of Cladosporium cladosporioides, Candida lipolytica, Nocardia globerula, Nocardia rubra and/or Saccharomyces cerevisiae until the PCBs have been substantially degraded. The process is applicable degrading PCBs as they may be present as pollutants or contaminants in water, in industrial effluents, in various land areas such as industrial sites and the like or in varied laboratory or commercial installations. The process may also be used to clean up and degrade mixtures of PCBs and various hydrocarbon oils or petrochemicals whenever their presence constitutes a deleterious pollution.