Comparative Genomics of Two Novel Bacillus Strains: Microbiomic Insights into the Sequences, Metabolomics, and Potential Safe Use in the Creation of Biopreparations.

Abstract

Background: Bacillus bacteria are often used in the production of biopreparations. Moreover, these bacteria can be used in agriculture as probiotics or starters for manufacturing fodder preserved by fermentation (silage). The ability of Bacillus bacteria to produce many biologically active molecules and metabolites with antimicrobial activity means that these bacteria can stimulate plant growth and restore the balance of the microbiome in the digestive system of certain animals.

Methods: Using molecular biological analysis, bioinformatic annotation, and metabolic profiling of whole genome sequences, we analyzed two promising candidates for creating biopreparations, i.e., two Bacillus strains, namely B. mucilaginosus 159 and B. subtilis 111. We compared the genomes of these two strains and characterized both their microbiomic and metabolomic features.

Results: We demonstrated that both strains lacked elements contributing to the formation of toxic and virulent properties; however, both exhibited potential in the biosynthesis of B vitamins and siderophores. Additionally, these strains could synthesize many antimicrobial substances of different natures and spectrums of action. B. mucilaginosus 159 could synthesize macrolactin H (an antibiotic from the polyketide group), mersacidin (a class II lanthipeptide), and bacilysin. Meanwhile, B. subtilis 111 could synthesize andalusicin (a class III lanthipeptide), bacilysin, macrolactin H, difficidin, bacillaene (a polyene antibiotic), fengycin (a lipopeptide with antifungal activity), and surfactin (another lipopeptide). Further, a unique pathway of intracellular synthesis of the osmoprotectant glycine betaine was identified in B. subtilis 111, with the participation of betaine aldehyde dehydrogenase (BetB); this is not widely represented in bacteria of the genus Bacillus. These compounds can increase osmotic stability, which may be key for manufacturing biological starters for silage preparation.

Conclusions: These two Bacillus strains are safe for use as probiotic microorganisms or starters in producing preserved fodder. However, B. subtilis 111 may be preferable due to a wider spectrum of synthesized antimicrobial substances and vitamins. Our findings exemplify using genomic technologies to describe the microbiomic and metabolomic characteristics of significant bacterial groups such as Bacillus species.