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 17β-estradiol and 17α-ethinylestradiol followed by a validated HPLC-DAD method

Abstract: This work aimed at studying the biodegradation of two estrogens, 17alpha -estradiol (E2) and 17beta -ethinylestradiol (EE2), and their potential metabolism to estrone (E1) by microbial consortia. The biodegradation studies were followed by High Performance Liquid Chromatography-Diode Array Detector (HPLC-DAD) using a specifically developed and validated method. Biodegradation studies of the estrogens (E2 and EE2) were carried out with activated sludge (consortium A, CA) obtained from a Wastewater Treatment Plant (WWTP) and with a microbial consortium able to degrade recalcitrant compounds, namely fluorobenzene (consortium B, CB). E2 was more extensively degraded than EE2 by CA whereas CB was only able to degrade E2. The addition of acetate as a supplementary carbon source led to a faster biodegradation of E2 and EE2. E1 was detected as a metabolite only during the degradation of E2. The 16S rRNA gene sequence analyses of strains recovered from the degrading cultures revealed the presence of the genera Pseudomonas, Chryseobacterium and Alcaligenes. The genera Pseudomonas and Chryseobacterium were retrieved from cultures supplied with E2 and EE2, while the genus Alcaligenes was found in the presence of E2, suggesting that they might be involved in the degradation of these compounds.

Sorption and microbial degradation of toluenediamines and methylenedianiline in soil under aerobic and anaerobic conditions

Abstract: Three of the major diamines, 2,4-toluenediamine (2,4-TDA), 2,6-toluenediamine (2,6-TDA), and 4,4'-methylenedianiline (4,4'-MDA), used as intermediates in the production of polyurethanes have been studied for their fate in soil. Previous literature has reported variable biodegradation of these industrially important compounds with no information on their expected fate in soil. Their sorption to two soils and biodegradation in soil under both aerobic and anaerobic conditions have been studied. Under aerobic and anaerobic conditions, sorption constants, K oc , for both isomers of TDA on loam soils were 500-1300 after 8 h of contact, and the corresponding K oc values for MDA were 3800-5700 after 8 h of contact. Both isomers of TDA and 4,4'-MDA appear to be sorbed only a little more strongly under aerobic than anaerobic conditions. The 14 carbon-labeled TDA isomers and MDA started to biodegrade immediately after mixing with aerobic soil with the recovery of 2-3% 14 CO 2 after only 3 days. The biodegradation slowed later with recovery of 11-14% 14 CO 2 after 28 days and an apparent 34-40% biodegradation after 1 year, based on loss of 14 C. Under anaerobic methanogenic conditions, no 14 CH 4 or 14 CO 2 was recovered from any of the diamines after 71 days of incubation.

Microbial degradation of high molecular weight polycyclic aromatic hydrocarbons

Abstract: The bacterial degradation of high molecular weight PAHs was investigated by isolating communities and individual strains from a PAH-contaminated site. Microbiological analysis of soils from Port Melbourne, Australia, resulted in the enrichment of five microbial communities capable of degrading pyrene as a sole carbon and energy source. Communities four and five degraded a number of PAH compounds including fluorene, phenanthrene, pyrene and dibenz[a,h]anthracene. Three pure cultures were isolated from community five using a spray plate method with pyrene as the sole carbon source. The cultures were identified as strains of Stenotrophomonas maltophilia on the basis of multiple sequence alignment analysis of 16SrRNA gene sequences. Differentiation of the three strains was possible by pulse field gel electrophoresis and DNA:DNA hybridisation methods. The St. maltophilia strains had similar degradative profiles to community five.

Aerobic Toluene Degraders in the Rhizosphere of a Constructed Wetland Model Show Diurnal Polyhydroxyalkanoate Metabolism

Abstract: Constructed wetlands (CWs) are successfully applied for the treatment of waters contaminated with aromatic compounds. In these systems, plants provide oxygen and root exudates to the rhizosphere and thereby stimulate microbial degradation processes. Root exudation of oxygen and organic compounds depends on photosynthetic activity and thus may show day-night fluctuations. While diurnal changes in CW effluent composition have been observed, information on respective fluctuations of bacterial activity are scarce. We investigated microbial processes in a CW model system treating toluene-contaminated water which showed diurnal oscillations of oxygen concentrations using metaproteomics. Quantitative real-time PCR was applied to assess diurnal expression patterns of genes involved in aerobic and anaerobic toluene degradation. We observed stable aerobic toluene turnover by Burkholderiales during the day and night. Polyhydroxyalkanoate synthesis was upregulated in these bacteria during the day, suggesting that they additionally feed on organic root exudates while reutilizing the stored carbon compounds during the night via the glyoxylate cycle. Although mRNA copies encoding the anaerobic enzyme benzylsuccinate synthase ( bssA ) were relatively abundant and increased slightly at night, the corresponding protein could not be detected in the CW model system. Our study provides insights into diurnal patterns of microbial processes occurring in the rhizosphere of an aquatic ecosystem. IMPORTANCE Constructed wetlands are a well-established and cost-efficient option for the bioremediation of contaminated waters. While it is commonly accepted knowledge that the function of CWs is determined by the interplay of plants and microorganisms, the detailed molecular processes are considered a black box. Here, we used a well-characterized CW model system treating toluene-contaminated water to investigate the microbial processes influenced by diurnal plant root exudation. Our results indicated stable aerobic toluene degradation by members of the Burkholderiales during the day and night. Polyhydroxyalkanoate synthesis in these bacteria was higher during the day, suggesting that they additionally fed on organic root exudates and reutilized the stored carbon compounds during the night. Our study illuminates microbial processes occurring in the rhizosphere of an aquatic ecosystem.