Engineering Bacillus subtilis ATCC 6633 for improved production of the lantibiotic subtilin

To improve the production of the lantibiotic subtilin in Bacillus subtilis ATCC 6633, two genetic engineering strategies were followed. Firstly, additional copies of subtilin self-protection (immunity) genes spaIFEG have been integrated into the genome of the producer strain. Their expression significantly enhanced the subtilin tolerance level, and concomitantly, the subtilin yield 1.7-fold. Secondly, a repressor of subtilin gene expression, the B. subtilis general transition state regulator protein AbrB, was deleted. A sixfold enhancement of the subtilin yield could be achieved with the abrB deletion mutant; however, the produced subtilin fraction predominantly consists of succinylated subtilin species with less antimicrobial activity compared to unmodified subtilin.