T. B. Karegoudar
Gulbarga University, India
T.B.Karegoudar, Professor of Biochemistry, working in the university for the past 28 years. He has focused his research on bioremediation of xenobiotics, microbial bioconversions and isolation of industrially important microbial enzymes and their applications. He has isolated and characterized several potential strains and deposited in the national cultural collections. He has successfully completed major projects funded by many national funding agencies. He has published more than 65 research publications in reputed journals. He has successfully guided 13 PhD students. He served as Chairman, Department of Biochemistry of Gulbarga University. He is in the review panel of several microbiology and biotechnology journals. He is an editorial member of few scientific journals.
A bacterial strain Paracoccus sp. SKG capable of utilizing aliphatic nitriles as a sole source of carbon and nitrogen was isolated. Degradation of nitriles follows the bi-enzymatic pathway with the successive action of nitrile hydratase (NHase) and amidase. The inducible amidase from cell-free extract of Paracoccus sp. SKG was purified and characterized. The amidase was purified to 93.0 fold with a recovery of 46.5% yield and an estimated molecular mass of 90 kDa. The purified amidase exhibits highest activity at pH 7.5 and temperature at 50oC. This enzyme is highly specific to aliphatic amides with highest activity to acetamide, propionamide and acrylamide, but not to aromatic amides. Among the metal ions studied, Mg2+, Mn2+ and Ni2+ ions increase the enzyme activity, whereas Cu2+ completely inhibited the amidase activity. In vitro inhibition of amidase was confirmed by preincubation of the whole cells Paracoccus sp. SKG with Cu2+. The use of amidase inhibited whole cells of Paracoccus sp. SKG was demonstrated as a biocatalyst for the conversion of acrylonitrile to acrylamide in a batch reaction. The bioconversion of acrylonitrile to acrylamide resulted in 27g/L of acrylamide with 65% of conversion under optimal conditions of pH (7.0) and temperature (30oC).