Isolation and Characterization of Bifidobacterium longum subsp. longum BCBL-583 for Probiotic Applications in Fermented Foods

Recent human gut microbiome studies have supported that the genus Bifidobacterium is one of the most beneficial bacteria for human intestinal health. To develop a new probiotic strain for functional food applications, fourteen fecal samples were collected from healthy Koreans and the strain BCBL-583 was newly selected and isolated from a 25-year-old Korean woman's fecal sample using the selective medium for Bifidobacterium. Subsequent fructose-6-phosphate phosphoketolase (F6PPK) test and 16S rRNA gene sequencing analysis of the strain BCBL-583 confirmed that it belongs to B. longum subsp. longum. The stress resistance tests showed that it has oxygen and heat tolerance activities (5- and 3.9-fold increase for 24 h at 60 and 120 rpm, respectively; 78.61 ± 6.67% survival rate at 45°C for 24 h). In addition, gut environment adaptation tests revealed that this strain may be well-adapted in the gut habitat, with gastric acid/bile salt resistance (85.79 ± 1.53%, survival rate under 6 h treatments of gastric acid and bile salt) and mucin adhesion (73.72 ± 7.36%). Furthermore, additional tests including cholesterol lowering assay showed that it can reduce 86.31 ± 1.85% of cholesterol. Based on these results, B. longum BCBL-583 has various stress resistance for survival during food processing and environmental adaptation activities for dominant survival in the gut, suggesting that it could be a good candidate for fermented food applications as a new probiotic strain.