Cloning and analysis of two alanine racemase genes fromBacillus licheniformis

Alanine racemase activity was investigated in the industrial organism Bacillus licheniformis . Two putative alanine racemase genes were identified from the genome sequence (which we denote alr and alr2 ) and these were cloned individually in E. coli . Expression of either of the cloned B. licheniformis genes in the alanine auxotrophic strain E. coli MB2159 complemented the mutant, restoring the ability of the recombinant host strain to grown on media such as LB without the addition of alanine. Alanine racemase activity was also directly detected in assays of cell-free extracts prepared from the recombinant strains. The results demonstrate that B. licheniformis encodes two separate alanine racemase enzymes.