Characterization of an Esterase Producing Bacterium from the Gut of Chironomus circumdatus (Bloodworms) and its Ability to Use Modified Phthalates.

Insects harbor bacteria that are a rich source of enzymes that can be utilized for various industrial and biotechnological applications. It is predicted that during evolution these detoxifying enzymes have been acquired by insects through bacteria. However, the role of host insect detoxification enzymes has already been extensively studied but only a few resistance development studies have been focused on the enzymes derived from gut bacteria. Thus in this study, two bacterial isolates were found in the gut of Chironomous circumdatus larvae having esterase activity, out of which one bacterium was molecular characterized and it was found to be Enterobacter mori designated as strain BI1245. Further, crude extract from the bacterium was characterized and it was observed that it showed maximum activity at pH 8 and temperature 60 °C. Moreover, the crude extract showed 0.26 mM and 290 U/mg of protein as Km and Vmax value when p-nitrophenyl acetate was used as a substrate. Thereafter, the bacterial isolate was incubated in minimal salts medium containing modified phthalates and it was found that bacterium could utilize shorter alkyl-chain phthalic acid esters faster as compared to long alkyl chains thereby indicating that side chain of the substrates has a significant effect on the utilization of phthalic acid esters. Thus the gut flora present in insects may play an important role in providing resistance to the host to live in phthalate polluted water.