HETEROGENOUS EXPRESSION OF POLY-y-GLUTAMIC ACID SYNTHETASE COMPLEX GENE OF Bacillus licheniformis WBL-3

摘要

Bacillus licheniformis WBL-3, one of poly-y-glutamic acid (y-PGA) producers, depends on the existence of glutamate in the medium. In this paper, y-PGA synthetase complex gene (pgsBCA) was cloned from Bacillus licheniformis WBL-3. pgsBCA gene of B. licheniformis WBL-3 was highly homologous with pgsBCA gene of B. licheniformis 14580. The similarity was 97%, but the similarity of pgsBCA gene between B. licheniformis WBL-3 and Bacillus subtilis IF03336 was only 74%. However, when pgsBCA was expressed inEscherichia coli, the E. coli clone produced y-PGA extracellularly. The yield of y-PGA was 8.624 g/1. This result infers that B. licheniformis and B. subtilis has the similar y-PGA biosynthesis mechanism, namely, glutamic acid is catalyzed by an ATP-dependent amide ligase to synthesize y-PGA.