Sublichenin, a new subtilin-like lantibiotics of probiotic bacterium Bacillus licheniformis MCC 2512T with antibacterial activity

Abstract

Probiotic bacteria with antibacterial activity is of desirable trait since they can check the growth of pathogenic bacteria besides exhibiting health benefits to host. Aim of this study was to characterize Bacillus licheniformis MCC 2512T (MCC 2512), a potential probiotic culture for its ability to produce subtilin-like antibiotics. The anti-microbial compound produced by MCC 2512 was identified and characterized using subtilin-specific cell reporter, Bacillus subtilis 168:BS2 (BS2). Induction of β-gal by the test culture suggested the ability of B. licheniformis to produce subtilin-like lantibiotic. Subsequently, DNA sequencing of major lanS-operon was carried out, wherein sequencing results showed that lan cluster of MCC 2512 resembles entianin (etn) type. Upon lan-S disruption, the bacterial culture lost antimicrobial activity as well as ability to induce β-gal with BS2 reporter. High amount of succinylated form of antibiotics produced by wild type and un-succinylated form by engineered strain of B. subtilis 15029p clearly indicates that MCC 2512 is indeed an inter-specific subtilin-like (named as sublichenin) lantibiotic producer. Partially concentrated sublichenin preparation exhibited strong antibacterial activity against food-borne pathogens and antibiotic resistant (AR) lactic acid bacteria (LAB) with a minimum inhibitory concentration in the range of 6–10 and 0.5–1.5 μg/ml, respectively. Production of lantibiotic, sublichenin by a probiotic bacterium of B. licheniformis MCC 2512T and its antibacterial activity against food associated AR LAB is a new information reported in this study.