Characterization of dual bacteriocins producing Bacillus subtilis SC3.7 isolated from fermented food
Pramila Epparti, Sachin M. Eligar, A. P. Sattur, B.S. Gnanesh Kumar, Prakash M. Halami
Abstract
The thermostable antimicrobial peptide with broad-spectrum inhibitory activity is of great interest due to its potential application as a biopreservative agent. In the present study, we characterized a Bacillus spp. isolated from fermented foods of Northeast region, India. The selective screening of bacteriocins producers was carried out using B. subtilis based whole-cell biosensors BSF2470 and BS168.BS2. Among 12 isolates showing bacteriocin production, culture with high antibacterial activity was subjected to whole-genome sequencing and referred to as B. subtilis strain SC3.7. Through genome annotation, two bacteriocin genes spaS and sboA, responsible for the synthesis of sublichenin and subtilosin A were identified. Further, mass spectrometric analysis confirmed the secretion of sublichenin (3346 Da), its succinylated form (3446 Da), and subtilosin A (3399 Da). Interestingly, a unique acyclic variant of subtilosin A (3417 Da) was also determined. The purified peptides were effective against various indicator strains at lower concentrations. Overall, the study reports a B. subtilis strain that produces two bacteriocins sublichenin and subtilosin A. This new combination of bacteriocins can be an effective biopreservative in the food industry.