Digestion of Tannin by Bacteria Enterobacter cloacae from the Gut ofIndian Mole Cricket (Gryllotalpa krishnani)

Insects are the most successful animal on earth; the gut microbes present might play an important role in food digestion as well as the interaction with hosts. In this study insect Gryllotalpa krishnani has been used to isolate the symbiotic associated organisms which play role in host metabolism, promote efficient digestion and to protect the host from the harmful microbes. In the present study, microorganisms were isolated from the gut of G. krishnani and characterized for tannase enzyme activity. It was observed that 5 isolates (TAH 6, TAH 13, TAH 36, TAH 38 and TAH 41) out of total 120 tested were able to show significant growth on tannic acid plate. Among these five potential isolates, strain TAH 41 exhibited maximum tannase activity in tannase plate assay and was selected for the further study. The bacterial strain TAH41 was analyzed for biochemical analysis, 16S rDNA sequencing and the result confirmed the strain as Enterobacter cloacae. HPLC analysis showed the formation two peaks representing gallic acid and glucose as a by-product FT-IR analysis also confirmed the same. The polyacrylamide gel electrophoresis (SDS-PAGE) and zymogram analysis showed the molecular mass of tannase enzyme in cell free extract was ~45 kDa, the analysis suggested this tannase enzyme to be one of the smallest of the bacterial source, which could be attributed to the formation of di or tri‑galloyl glucose. The present study was the first report E. cloacae with tannase activity from G. krishnani gut. E. cloacae which may endow the insect with some ecological advantages by enabling them to overcome the anti-nutritional effects of plant tannins.