Abstract

Mutagenesis is an essential way to dissect gene’s physiological functions and characterizations in vivo. In this paper, a novel vector designated pAK12 was constructed for generating gene inactivation mutant in gram-positive Bacillus cereus. By using two-step strategy, a plcR gene knock-out mutant in B. cereus 1N21 was obtained without antibiotic resistance gene inside. The genetic evidences and phynotypic differences confirmed plcR gene was disrupted and inactivated in B. cereus 1N21. Biofilm formation in exopolysaccharide (EPS) by the plcR mutant was about four times higher than that by the wild-type strain. This novel gene knock-out system could be used for genetic mutagenesis in gram-positive bacterium efficiently.

Key words: Bacillus cereus, allele exchange mutagenesis, pleiotropic regulator.