Bacillus licheniformis MCC 2514 genome sequencing and functional annotation for providing genetic evidence for probiotic gut adhesion properties and its applicability as a bio-preservative agent

Abstract

Bacillus licheniformis is a well-known probiotic that can be found in a variety of foods. The strain Bacillus licheniformis MCC 2514 was previously characterized by our group for its bio-physiological capabilities establishing it as a promising probiotic, but information on the genetic evidence for its attributes was lacking. In the current study, whole genome analysis identified the underlying molecular determinants responsible for its probiotic potential. The circular genome of MCC 2514 was 4,230,480 bp with 46.2% GC content, 24 rRNA, and 83 tRNA genes. The pangenome analysis between B. licheniformis MCC 2514 and 12 other B. licheniformis strains revealed a pangenome of 6008 genes and core genome of 3775 genes. Genome mining revealed NRPS and bacteriocins producing gene clusters indicating its biocontrol properties. Several genes encoding carbohydrate degrading enzymes, which aid in proper food degradation in the intestine, were also observed. Stress tolerance, vitamin, and essential amino acids biosynthesis related genes were found, which are important characteristics of a probiotic strain. Additionally, vital genes responsible for gut adhesion and biofilm formation were observed in its genome. The bacterium has been shown to improve the shelf life of idli batter by preventing whey separation, CO2, and odour production while maintaining the pH of 3.96–4.29, especially at cold temperatures. It has significantly reduced coliform contamination at both room and low temperatures, demonstrating its bio-preservative ability, which is also corroborated by the presence of the NRPS and bacteriocin gene clusters in its genome. The present study helped to understand both, the ability of B. licheniformis MCC 2514 to adapt the intestinal gut environment and its probiotic functionality for food preservation.