T B Karegoudar
Title: Purification and characterization of amidase from Paracoccus sp. SKG: Utilization of amidase inhibited whole cells for bioconversion of acrylonitrile to acrylamide
Biography
Biography: T B Karegoudar
Abstract
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 50o C. 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 pre-incubation 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 27 g/L of acrylamide with 65% of conversion under optimal conditions of pH (7.0) and temperature (30o C).