Genetic improvement of α-amylase producing Bacillus licheniformis by homolog-mediated α-amylase gene amplification

Abstract:

Bacillus licheniformis a-amylase (BLA) is one of the most important enzymes involved in starch hydrolysis and many biotechnological processes. To improve the BLA productivity, an integrative plasmid pBL-amyL carrying amyL gene encoding a thermophilic a-amylase of B. licheniformis was constructed and transformed into B. licheniformis B0204, an industrial α-amylase producer. The transformants harboring different copies of amyL were developed on kanamycin by using homolog-mediated chromosomal amplification of a-amylase gene. The recombinants with different multiple copies of amyL integrated in the chromosome were identified by real-time PCR and evaluated by shake-flask fermentation. Recombinants harboring 2?5 multiple copies of amyL produced more a-amylase comparison to the parental strain B0204.