ICAR Research Data Repository for Knowledge Management

In general, the presence of nitroaromatic compounds in nature is a major consequence of anthropogenic activities. Nitroaromatic compounds are used a herbicides, fungicides, bactericides, explosives and dyes. The combustion of petroleum products and other organic substances also generate nitroaromatics. Considerable amount of these compounds have been found to accumulate in soil by the hydrolysis of organophosphorus insecticides such as parathion or of herbicide nitrophenols Nitroaromatic compounds are detected as contaminants in river water and in large amounts in industrial waste waters Mononitrophenols such as o-Nitrophenol and p-Nitrophenol have been listed as priority pollutants by the US Environmental Protection Agency . The presence of the nitro group causes such compounds to be more resistant to biodegradation than the unsubstituted analogs and they tend to accumulate in the environment and cause deleterious effects to the biological systems due to their toxicity. Fresh and marine waters, sewage and soils posses highly diverse microbial communities that exhibit degradative capacities and species within these communities transform many organic compounds aerobically or anaerobically.Nitroaromatic compounds have been reported to be used by microorganisms as carbon, energy and nitrogen sources . A mixed bacterial system isolated from a contaminated soil sample was employed during the present study on individual and simultaneous degradation of mononitrophenol isomers - o-Nitrophenol(ONP), m-Nitrophenol(MNP) and p-Nitrophenol (PNP).A brief introduction to nitroaromatic compounds and detail review of literature regarding the biodegradation of these compounds both aerobically and anaerobically by various microorganisms and specially bacteria has been discussed. Emphasis is also laid on the different mechanisms involved in degradation. Factors that affect biodegradation such as carbon and nitrogen sources, inorganic nutrients, acclimation period, inoculum size, substrate concentration, adaptation, varying pH and temperature conditions have been dealt with. It also includes a brief introduction on the characteristics of the mononitrophenol isomers and the objective of studying their degradation.Degradation of the three mononitrophenol isomers and their mixture using a consortium have been studied. Conclusions from the degradation studies of mononitrophenol isomers carried out by the mixed bacterial culture and the individual culture Sarcina maxima (SNP-8) and the scope for future research in the field of biodegradation studies have also been discussed.