Perspective of Streptococcus thermophilus Strains as New Probiotics Derived from the Breast Milk of Indian Mothers

Abstract

ABSTRACT In this study, two lactic acid bacterial cultures were isolated from human milk, and their probiotic attributes were evaluated. The 16S rRNA technique confirmed that the isolates share close homology to Streptococcus thermophilus and are designated as HN2 and HN3 strains. Both cultures showed significant tolerance, i.e. 74–92% and 66–88% survivability in acidic and bile conditions, respectively (p < 0.05). The hydrophobicity values ranged from 26–39% against hydrocarbons, auto-aggregation (40–51%), and β-galactosidase activity (43–102 U/mL) were observed, while antagonistic activity against pathogens ranged between 12–26 mm. The antibiotic profile demonstrated that the HN3 strain was more resistant compared to the HN2 strain. The antioxidant activities of supernatant and intact cells were determined using DPPH and ABTS method and found between 37–89%. The safety parameters data revealed that hemolytic reaction and mucin degradation were not detected. The findings suggested that the strains could be potentially targeted in functional foods for therapeutic applications following further in vivo studies.