Microbial biodegradation

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

Pathway Dependent Isotopic Fractionation during Aerobic Biodegradation of 1,2-Dichloroethane

Abstract: 1,2-Dichloroethane (1,2-DCA) is a widespread groundwater contaminant known to be biodegradable under aerobic conditions via enzymatic oxidation or hydrolytic dehalogenation reactions. Current literature reports that stable carbon isotope fractionation of 1,2-DCA during aerobic biodegradation is large and reproducible (−27 to −33‰). In this study, a significant variation in the magnitude of stable carbon isotope fractionation during aerobic biodegradation was observed. Biodegradation in experiments involving microcosms, enrichment cultures, and pure microbial cultures produced a consistent bimodal distribution of enrichment factors (e) with one mean e centered on −3.9 ± 0.6‰ and the other on −29.2 ± 1.9‰. Reevaluation of e in terms of kinetic isotope effects 12k/13k gave values of 12k/13k = 1.01 and 1.06, which are typical of oxidation and hydrolytic dehalogenation (SN2) reactions, respectively. The bimodal distribution is therefore consistent with the microbial degradation of 1,2-DCA by two separate enzym...

Biodegradation of the sulfonylurea herbicide chlorimuron-ethyl by the strain Pseudomonas sp. LW3

Abstract: The chlorimuron-ethyl-degrading bacterium LW3 was isolated from contaminated soil and identified by 16S rRNA gene sequencing as Pseudomonas sp When chlorimuron-ethyl was provided as the sole nitrogen source, the degradation efficiency in liquid medium was about 810% after 7 days of inoculation with strain LW3 The effects of chlorimuron-ethyl concentration and temperature on biodegradation were examined Two metabolites of degradation were analyzed by LC/MS Based on the identified products, strain LW3 seemed to be able to degrade chlorimuron-ethyl by cleavage of the sulfonylurea bridge The inoculation of strain LW3 to chlorimuron-ethyl-treated soil resulted in a higher degradation rate than in uninoculated soil, regardless of the soil being sterilized or nonsterilized This microbial culture has great potential for the bioremediation of soil contaminated with chlorimuron-ethyl

Effect of Model Sorptive Phases on Phenanthrene Biodegradation: Different Enrichment Conditions Influence Bioavailability and Selection of Phenanthrene-Degrading Isolates

Abstract: The sorption of organic contaminants by natural organic matter (NOM) often limits substrate bioavailability and is an important factor affecting microbial degradation rates in soils and sediments. We hypothesized that reduced substrate bioavailability might influence which microbial assemblages are responsible for contaminant degradation under enrichment culture conditions. Our primary goal was to characterize enrichments in which different model organic solid phases were used to establish a range of phenanthrene bioavailabilities for soil microorganisms. Phenanthrene sorption coefficients (expressed as log KD values) ranged from 3.0 liters kg 21 for Amberlite carboxylic acid cation-exchange resin (AMB) to 3.5 liters kg 21 for Biobeads polyacrylic resin (SM7) and 4.2 liters kg 21 for Biobeads divinyl benzene resin (SM2). Enrichment cultures were established for control (no sorptive phase), sand, AMB, SM7, and SM2 treatments by using two contaminated soils (from Dover, Ohio, and Libby, Mont.) as the initial inocula. The effects of sorption by model phases on the degradation of phenanthrene were evaluated for numerous transfers in order to obtain stable microbial assemblages representative of sorptive and nonsorptive enrichment cultures and to eliminate the effects of the NOM present in the initial inoculum. Phenanthrene degradation rates were similar for each soil inoculum and ranged from 4 to 5 mmol day 21 for control and sand treatments to approximately 0.4 mmol day 21 in the presence of the SM7 sorptive phase. The rates of phenanthrene degradation in the highly sorptive SM2 enrichment culture were insignificant; consequently, stable microbial populations could not be obtained. Bacterial isolates obtained from serial dilutions of enrichment culture samples exhibited significant differences in rates of phenanthrene degradation performed in the presence of SM7, suggesting that enrichments performed in the presence of a sorptive phase selected for different microbial assemblages than control treatments containing solid phase phenanthrene.