Bioremediation of biphenyl and chlorinated biphenyls in transformer oil contaminated soil by a bacterial consortium and genomic evidences for its survival

Abstract

The presence of persistent organic pollutants POPs in the environment is one of the fast growing issues of global nature due to unregulated disposal and informal recycling of recalcitrant compounds In India the use of PCB containing transformer oil TO in power sectors was put forth since the commercial production of PCBs began in late 1920s The composition of TO includes polychlorinated biphenyls PCBs polyaromatichydro carbons PAHs chlorinated phenols and heavy metals that have longer half life and persistence in the environment PCBs are complex mixtures witha class of 209 congeners The US Environmental Protection Agency and the International Agency for Research on Cancer IARC recognized PCBs as carcinogens and revealed the storage of about 10000 tonnes of PCBs in the Indian Power sector PCBs were never produced in India and the import of PCBs into the country was banned in 1998 The estimated quantity of PCB containing equipment and pure PCB oils in India today amounts to about10000 15000 tonnes As per the Stockholm Convention India has to eliminate PCBs by 2025 however no technology is available in India for the sound disposal of PCBs Though the commercial production of PCB was banned worldwide its release from historic uses in advertent production during manufacturing process and the release of newly generated PCBs into environment thus become a great challenge Biological method of removal of PCB is one of the eco friendly and economic method for removal of PCBs from contaminated site Many indigenous microbes can utilize these PCBs Although the indigenous bacteria were shown to possess degrading efficiency due to a wide variety of environmental stress factors these organisms attain a viable but non culturable VBNC state The presents study focusses on isolating such indigenous group of bacteria capable of degrading biphenyls and chlorinated biphenyls analysis of PCBs PAH phenolic compounds and heavy metals in transformer oil contaminated soil bioremediation of transformer oil contaminated soil and identification