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 in soil microcosms of fuel oil hydrocarbons from drilling cuttings.

Abstract: The biodegradation of the fuel oil hydrocarbons contained in drilling cuttings was studied in soil microcosms during a 270-day experiment. Concentration and chemical composition of residual hydrocarbons were periodically monitored by quantitative capillary gas chromatography. The decrease in hydrocarbon concentration was logarithmic with time. At the end of the experiment, the fuel oil was 75% degraded. In the saturated fraction, normal and branched alkanes were almost totally eliminated in 16 days ; 22% of the cycloalkanes were not assimilated. The aromatic fraction was 71% degraded ; some polycyclic aromatics were persistent. The resin fraction (10% of the initial weight) was completely refractory to biodegradation. The inorganic part of drilling cuttings had no influence on the biodegradation rates of hydrocarbons. Biogenic hydrocarbons and traces of degradable fuel oil hydrocarbons were protected from microbial activity by the soil and cuttings matrix. Enumerations of total heterotrophic bacteria and hydrocarbon-utilizing bacteria showed a strong stimulation in both populations. Hydrocarbon-degrading strains of bacteria and fungi were isolated and identified at the generic or specific level.

Fungal biodegradation of a phenylurea herbicide, diuron: structure and toxicity of metabolites

Abstract: Microbial degradation, organic synthesis and ecotoxicology were used to investigate the fate of diuron after spreading on soils. Quantitative biodegradation assays were performed with fungal strains, showing that diuron was degraded but not entirely mineralized. The modifications observed consisted in demethylation of the terminal nitrogen atom. The identified metabolites were synthesized in sufficient amounts to confirm their structures and determine their non-target toxicity using four biotests. The two metabolites exhibited higher effects than parent diuron. This limited biodegradability and potential aquatic toxicity suggest that diuron is of higher environmental concern than previously recognized.

Reconstructing metabolic pathways of hydrocarbon-degrading bacteria from the Deepwater Horizon oil spill

Abstract: The Deepwater Horizon blowout in the Gulf of Mexico in 2010, one of the largest marine oil spills(1), changed bacterial communities in the water column and sediment as they responded to complex hydrocarbon mixtures(2-4). Shifts in community composition have been correlated to the microbial degradation and use of hydrocarbons(2,5,6), but the full genetic potential and taxon-specific metabolisms of bacterial hydrocarbon degraders remain unresolved. Here, we have reconstructed draft genomes of marine bacteria enriched from sea surface and deep plume waters of the spill that assimilate alkane and polycyclic aromatic hydrocarbons during stable-isotope probing experiments, and we identify genes of hydrocarbon degradation pathways. Alkane degradation genes were ubiquitous in the assembled genomes. Marinobacter was enriched with n-hexadecane, and uncultured Alpha- and Gammaproteobacteria populations were enriched in the polycyclic-aromatic-hydrocarbon-degrading communities and contained a broad gene set for degrading phenanthrene and naphthalene. The repertoire of polycyclic aromatic hydrocarbon use varied among different bacterial taxa and the combined capabilities of the microbial community exceeded those of its individual components, indicating that the degradation of complex hydrocarbon mixtures requires the non-redundant capabilities of a complex oil-degrading community.

13C/12C isotope fractionation of aromatic hydrocarbons during microbial degradation

Abstract: The influence of microbial degradation on the 13C/12C isotope composition of aromatic hydrocarbons is presented using toluene as a model compound. Four different toluene-degrading bacterial strains grown in batch culture with oxygen, nitrate, ferric iron or sulphate as electron acceptors were studied as representatives of different environmental redox conditions potentially prevailing in contaminated aquifers. The biological degradation induced isotope shifts in the residual, non-degraded toluene fraction and the kinetic isotope fractionation factors alphaC for toluene degradation by Pseudomonas putida (1.0026 +/- 0.00017), Thauera aromatica (1.0017 +/- 0.00015), Geobacter metallireducens (1.0018 +/- 0.00029) and the sulphate-reducing strain TRM1 (1.0017 +/- 0.00016) were in the same range for all four species, although they use at least two different degradation pathways. A similar 13C/12C isotope fractionation factor (alphaC = 1.0015 +/- 0.00015) was observed in situ in a non-sterile soil column in which toluene was degraded under sulphate-reducing conditions. No carbon isotope shifts resulting from soil-hydrocarbon interactions were observed in a non-degrading soil column control with aquifer material under the same conditions. The results imply that microbial degradation of toluene can produce a 13C/12C isotope fractionation in the residual hydrocarbon fraction under different environmental conditions.