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A genome-based systematic analysis combined with phenotypic experiments was conducted to evaluate the safety properties and metabolic characteristics of Streptococcus thermophilus DMST-H2, isolated from Chinese traditional homemade yogurt in Inner Mongolia. Comparative genomic analysis showed that DMST-H2 had a closer genetic relationship with S. thermophilus KLDS.3.1003 based on the sequence similarities of the 1193 core-genes. No genes related to antibiotic resistance and virulence factor as well as no complete biogenic amine biosynthesis gene clusters were identified in DMST-H2 genome. DMST-H2 was sensitive to various antibiotics and had no hemolytic activity and no biogenic amine production capacity, confirming that DMST-H2 is safe and non-toxic. In addition, multiple genes for carbohydrate metabolism were predicted, including various carbohydrate-active enzymes and sugar transporters that could be involved in the transport of multiple carbon sources. Two exopolysaccharide (EPS) gene clusters (eps-1 and rgp-2) were also detected, indicating that DMST-H2 has the potential to synthesize heteropolysaccharides. Gene functional features revealed a cyclic antimicrobial peptide related gene cluster in DMST-H2, which displayed high identities with the streptide biosynthesis gene cluster as previously reported. Our comprehensive analysis of the whole genome and corresponding phenotypes of S. thermophilus DMST-H2 provides important theoretical basis for its application in food products. • Comparative genomic analysis of S. thermophilus DMST-H2 was displayed. • Systematic analysis of its safety and metabolism characteristics based on phenotype and genotype. • Two exopolysaccharide (EPS) gene clusters were found in the genome of S. thermophilus DMST-H2. • Carbohydrate metabolism pathways were predicted in the genome of S. thermophilus DMST-H2. [ABSTRACT FROM AUTHOR]

Lactobacillus gasseri is a kind of facultative anaerobic lactic acid bacterium, and has been defined as GRAS microorganism by the US Food and Drug Administration. We reported the whole genome sequence of L. gasseri LGZ1029. The complete genome of L. gasseri LGZ1029 was 2,027,325 bp encoding 2005 genes with an average G + C content of 35.06%. Based on the analysis of genes involved in antibiotic resistance, virulence factor, and production of harmful metabolites, we have speculated that L. gasseri LGZ1029 is safe. By genome mining tool, a complete plnABCD operon was present in the genome of L. gasseri LGZ1029, indicating that it has the potential to generate antimicrobial bacteriocin. Stress-related genes speculated that L. gasseri LGZ1029 had good gastrointestinal tolerance, bacteriostatic ability, and antioxidant activity with excellent probiotic characteristics, indicating that it can be a probiotic candidate with great potential. • Complete genome of L. gasseri LGZ1029 was firstly sequenced. • The safety and probiotic properties of L. gasseri LGZ1029 were evaluated by genome analysis. • A complete plnABCD operon was found in the genome of L. gasseri LGZ1029. • Stress response genes were identified in the genome of L. gasseri LGZ1029. [ABSTRACT FROM AUTHOR]