Transformation of amides by adherent Rhodococcus cells possessing amidase activity

Abstract

We report the development of a heterogeneous biocatalyst for the hydrolysis of amides that is based on cell adhesion of amidase-containing Rhodococci on activated birch charcoal (ABC) and raw coal. We investigated the properties of the obtained biocatalyst in the hydrolysis reaction of acrylamide to acrylic acid and nicotinamide to nicotinic acid, as well as in a model reaction of racemic lactamide hydrolysis to a mixture of D- and L-isomers of lactic acid. We show that a six- and threefold increase in the concentrations of adherent and suspended cells, respectively, results in a reduction of amidase activity by 3 and 30 times, respectively. Cells adherent on ABC maintained more than 50% of enzymatic activity for seven 24-hour cycles of acrylamide hydrolysis, while suspended cells lost more than 60% of activity already in the second cycle. We also noted that cell adhesion on ABC reduced the stereoselectivity of hydrolysis reaction of racemic lactamide.