Engineering of Bacillus subtilis 168 for Increased Nisin Resistance

Abstract

Nisin is a natural bacteriocin produced commercially by Lactococcus lactis and widely used in the food industry as a preservative because of its broad host spectrum. Despite the low productivity and troublesome fermentation of L. lactis, no alternative cost-effective host has yet been found. Bacillus subtilis had been suggested as a potential host for the biosynthesis of nisin but was discarded due to its sensitivity to the lethal action of nisin. In this study, we have reevaluated the potential of B. subtilis as a host organism for the heterologous production of nisin. We applied transcriptome and proteome analyses of B. subtilis and identified eight genes upregulated in the presence of nisin. We demonstrated that the overexpression of some of these genes boosts the natural defenses of B. subtilis, which allows it to sustain higher levels of nisin in the medium. We also attempted to overcome the nisin sensitivity of B. subtilis by introducing the nisin resistance genes nisFEG and nisI from L. lactis under the control of a synthetic promoter library.

The Bacillus subtilis GntR Family Repressor YtrA Responds to Cell Wall Antibiotics

“…Conversely, in other cases, antibioticinducible genes do not confer an obvious protective effect. For example, no susceptibility changes were observed with the liaIH-null mutant when treated with either vancomycin or nisin, both of which strongly induce these genes (14,44). This may be due, in part, to functional redundancy.…”

“…Most of these induced genes are controlled by W and M . Similarly, treatment with bacitracin, nisin, and ramoplanin strongly induced LiaRS and its regulon liaIHGSF (14,27,28). Null mutations in the induced regulators or regulon members often, but not always, result in higher susceptibility to antibiotics.…”

The ABC Transporter AnrAB Contributes to the Innate Resistance of Listeria monocytogenes to Nisin, Bacitracin, and Various β-Lactam Antibiotics

“…ABC transporters other than LanEF proteins have also been linked to lantibiotic resistance. Gene expression studies have established that ABC transporter genes are overexpressed in a nisin-hyperresistant Lactococcus lactis strain (ysaBC) (26), a Bacillus subtilis strain subjected to nisin stress (yvcRS) (21), and a Staphylococcus aureus strain exposed to the lantibiotic mersacidin (vraDE) (41). Notably, in Streptococcus pneumoniae, the ABC transporter-encoding genes sp0913 and sp0912 are required for resistance to nisin and other antimicrobials (31).…”

Assessing the Contributions of the LiaS Histidine Kinase to the Innate Resistance of Listeria monocytogenes to Nisin, Cephalosporins, and Disinfectants

“…Indeed, with this knowledge, it may be possible to develop approaches to enhance the sensitivity of strains which are innately resistant. Many of the genes involved in nisin resistance fall into one of three subgroups: those which impact on the general composition of the cell envelope (38,45), various transporters (11,23,27), or regulators and two-component signal transduction systems (2CS). 2CS not only play a role in nisin resistance, but some also have been linked to cephalosporin resistance and resistance to environmental stresses (6,18,20,26).…”