Efficient bacterial cell factories are important for the screening and characterization of potent antimicrobial peptides such as lantibiotics. Although lantibiotic production systems have been established in Lactococcus lactis and Escherichia coli, the industrial workhorse Bacillus subtilis has been left relatively unexplored as a lantibiotic production host. Therefore, we tested different B. subtilis strains for their ability to produce lantibiotic peptides by using the subtilin modification and transport enzymes derived from the natural subtilin producer B. subtilis ATCC 6633. Our study shows that although B. subtilis ATCC 6633 and 168 are able to produce various processed lantibiotic peptides, an evident advantage of using either the 8-fold protease-deficient strain WB800 or the genome-minimized B. subtilis 168 strain PG10 is the lack of extracellular serine protease activity. Consequently, leader processing of lantibiotic precursor peptides is circumvented and thus potential toxicity toward the production host is prevented. Furthermore, PG10 provides a clean secondary metabolic background and therefore appears to be the most promising B. subtilis lantibiotic production host. We demonstrate the production of various lantibiotic precursor peptides by PG10 and show different options for their in vitro activation. Our study thus provides a convenient B. subtilis-based lantibiotic production system, which facilitates the search for novel antimicrobial peptides.
Keywords: expression systems; extracellular serine proteases; lantibiotics; microbial cell factory; miniBacillus.