Optimization of aspartate ammonia lyase production by Bacillus cereus

Abstract

In an attempt to clarify the function of L-aspartic acid and culture conditions in aspartate ammonia lyase induction, experiments were carried out on aspartase formation in Bacillus cereus cells. The enzyme was produced by microorganisms in response to L-aspartic acid, which is catabolized by direct deamination to fumarate. Enzyme synthesis by B. cereus was associated with physiological growth stages, which was confirmed by use of the protein synthesis inhibitor, chloramphenicol, whereas it did not influence synthesis when it was added directly to the reactor batch containing a biotransformation system. Aspartase activity was evaluated in a batch reactor by biotransformation of fumaric acid into L-aspartic acid catalyzed by whole B. cereus cells. The culture medium for the strain was optimized, which increased the initial aspartase activity threefold. B. cereus cells showed optimal aspartase activity at late log phase.