Expression and inducibility of endosulfan metabolizing gene in Rhodococcus strain isolated from earthworm gut microflora for its application in bioremediation

The metabolizing potential of a bacterial strain Rhodococcus MTCC 6716, isolated from the gut of an Indian earthworm (Metaphire posthuma) was studied for endosulfan bioremediation. In the present work, the optimum conditions for the maximum growth, kinetic of endosulfan degradation, regression equation, half life and correlation coefficient were studied. Endosulfan induced alterations in the expression of mRNA and protein of specific endosulfan metabolizing marker gene (Esd) was studied. Maximum growth of bacteria was observed at pH 7.0, 30 degrees C and 0.085 M sodium chloride concentration in a liquid culture medium. Endosulfan was degraded by Rhodococcus strain up to 97.23% within 15 days without producing toxic metabolite and with strong correlation coefficient (-0.728) and half life 5.99 days. Endosulfan degradation was mediated through gene(s) present in genomic DNA. Expression of marker gene was found endosulfan concentration dependent. The results suggest that this novel strain (Rhodococcus) may be utilized for bioremediation of endosulfan. (C) 2010 Elsevier Ltd. All rights reserved.