Whole-genome DNA sequencing of Lactobacillus D75 and D76 strains (Vitaflor, Russia) was determined using the PacBio RS II platform, which was followed by de novo assembly with SMRT Portal 2.3.0. The average nucleotide identity (ANI) test showed that both strains belong to the Lactobacillus helveticus, but not to the L. acidophilus, as previously assumed. In addition, 31 exopolysaccharide (EPS) production genes (nine of which form a single genetic cluster), 13 adhesion genes, 38 milk protein and 11 milk sugar utilization genes, 13 genes for and against specific antagonistic activity, eight antibiotic resistance genes, and also three CRISPR blocks and eight Cas I-B system genes were identified in the genomes of both strains. The expression of bacteriocin helveticin J genes was confirmed. In fact, the presence of identified genes suggests that L. helveticus D75 and D76 are able to form biofilms on the outer mucin layer, inhibit the growth of pathogens and pathobionts, utilize milk substrates with the formation of digestible milk sugars and bioactive peptides, resist bacteriophages, show some genome-determined resistance to antibiotics, and stimulate the host’s immune system. Pathogenicity genes have not been identified. The study results confirm the safety and high probiotic potential of the strains.

Lactobacillus helveticus D75 and D76 were isolated from the intestinal tract of a healthy child. Both strains possess symbiotic, probiotic, and antagonistic activities. We have sequenced and annotated the whole genomes of L. helveticus D75 and D76 and have conducted a preliminary genome comparative analysis.

Whole-genome DNA sequencing of Lactobacillus D75 and D76 strains (Vitaflor, Russia) was performed using the PacBio RS II platform, followed by de novo assembly with SMRT Portal 2.3.0. The average nucleotide identity (ANI) test showed that both strains belong to the Lactobacillus helveticus, but not the L. acidophilus as previously assumed. 31 exopolysaccharide (EPS) production genes (nine of which form a single genetic cluster), 13 adhesion genes, 38 milk protein and 11 milk sugar utilization genes, 13 genes for and against specific antagonistic activity, aight antibiotic resistance genes, and also three CRISPR blocks and eight Cas I-B system genes were identified in the genomes of the both strains. The expression of some genes was confirmed. In fact, the presence of identified genes suggests that L. helveticus D75 and D76 are able to form biofilms on the outer mucin layer, inhibit the growth of pathogens and pathobionts, utilize milk substrates with the formation of digestible milk sugars and bioactive peptides, resist bacteriophages and show some genome-determined resistance to antibiotics, stimulate the host’s immune system. Pathogenicity genes have not been identified. The study results confirm the safety and high probiotic potential of the strains.