Soy fermentation by indigenous oral probiotic Streptococcus spp. and its antimicrobial activity against oral pathogens

The present work aimed to determine the antagonistic effect of probiotic-fermented soy against oral pathogens. Indigenous oral probiotics (Streptococcus salivarius Taylor's University Collection Centre (TUCC) 1251, S. salivarius TUCC 1253, S. salivarius TUCC 1254, S. salivarius TUCC 1255, and S. orisratti TUCC 1253) were incorporated into soy fermentation at 37°C for 24 h. Growth characteristics, β-glucosidase activity, and total isoflavones content of Streptococcus strains following soy fermentation were analysed. Antimicrobial test of Streptococcus-fermented soy was carried out against oral pathogens Enterococcus faecalis American Type Culture Collection (ATCC) 700802, Streptococcus pyogenes ATCC 19615, and Staphylococcus aureus ATCC 25923. Streptococcus strains showed a significant increase in growth following soy fermentation. S. salivarius TUCC 1253-fermented soy showed significantly higher extracellular β-glucosidase activity and amount of aglycones. S. salivarius TUCC 1253-fermented soy showed antimicrobial effect against all oral tested pathogens in both aerobic and anaerobic conditions. These results showed that S. salivarius TUCC 1253-fermented soy could potentially be used as a preventive action or alternative treatment for oral infections.