Microbial biodegradation

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

Biodegradation of Organic Xenobiotic Pollutants in the Rhizosphere

Abstract: Soil contamination by xenobiotic organic compounds is a serious problem in most industrialized countries, causing acute and diffuse contamination of soil and waters on a global scale. Microbial transformation plays a major role in contaminant degradation of many persistent organic pollutants (POPs). However, microbial degradation can be limited by factors such as contaminant ­bioavailability, - ­adsorption and mass transfer, while combined plant-microbial systems can overcome these drawbacks, leading to more efficient contaminant degradation at the soil-root interface or rhizosphere. Hypotheses that support improved degradation within the rhizosphere compared to nonvegetated soils include (i) increase in microbial density, diversity and/or metabolic activity, (ii) catabolic enzyme induction, (iii) co-metabolism of contaminants with similar structures to rhizodeposits, (iv) improved contaminant bioavailability, and (v), selective increase in the number and activity of pollutant degraders. Root exudates or rhizodeposits not only provide a nutrient-rich habitat for microorganisms but can potentially enhance biodegradation of xenobiotics in different ways: they may facilitate the co-metabolic transformation of pollutants with similar structures, induce genes encoding enzymes involved in the degradation process, increase contaminant bioavailability, and/or selectively increase the number and activity of pollutant degraders in the rhizosphere. The combination of microbial bioremediation and phytoremediation in this complementary manner is known as rhizoremediation, phytostimulation or rhizosphere bioremediation. Bacteria, fungi and mycorrhizal fungi are a major component of the rhizosphere and form mutualistic associations with most plant species and their involvement in the biotransformation and biodegradation of various xenobiotic organic compounds is discussed. The diversity of bacterial and fungal genes and degradation pathways expressed in the rhizosphere is potentially huge, and the ways in which plants and associated symbionts enhance biodegradation remains much unexplored. Although a wide range of microbes able to degrade highly stable, toxic organic compounds such as polycyclic and aliphatic hydrocarbons have been discovered, the environmental pollution caused by these compounds remains an unsolved problem.

Microbial degradation of hydrochlorofluorocarbons (CHCl2F and CHCl2CF3) in soils and sediments.

Abstract: The ability of microorganisms to degrade trace levels of the hydrochlorofluorocarbons HCFC-21 and HCFC-123 was investigated. Methanotroph-linked oxidation of HCFC-21 was observed in aerobic soils, and anaerobic degradation of HCFC-21 occurred in freshwater and salt marsh sediments. Microbial degradation of HCFC-123 was observed in anoxic freshwater and salt marsh sediments, and the recovery of 1,1,1-trifluoro-2-chloroethane indicated the involvement of reductive dechlorination. No degradation of HCFC-123 was observed in aerobic soils. In some experiments, HCFCs were degraded at low (parts per billion) concentrations, raising the possibility that bacteria in nature remove HCFCs from the atmosphere.