Background
Specific probiotic bacteria may have inhibitory effects against oral pathogens. Lactobacillus spp. have been researched worldwide and are used in probiotics, but due to difficulties with laboratory cultivation of and experimentation on oral microorganisms, there are few reports of Lactobacillus spp. being isolated from the oral cavity and tested against oral pathogens. This research aimed to determine the safety and inhibitory impacts of L. gasseri HHuMIN D as a potential oral probiotic with biotherapeutic capabilities against oral pathogens.
Results
The microbial and genetic characteristics of L. gasseri HHuMIN D were evaluated in this research. A 5% dilution of L. gasseri HHuMIN D culture supernatant exhibited 88.8% inhibition against halitosis-producing anaerobic microorganisms and L. gasseri HHuMIN D exhibited powerful inhibitory effects on the growth of every harmful oral bacterium tested. Unfortunately, other oral bacteria affected the growth of L. gasseri HHuMIN D, suggesting a poor proliferative response to most co-cultures. Hydrogen peroxide production by L. gasseri HHuMIN D reached 802 µmol/L after 12 hours and gradually diminished until 24 hours. It efficiently aggregated with P. catoniae and S. sanguinis, and completely supressed S. mutans-manufactured artificial dental plaque. L. gasseri HHuMIN D’s KB cell adhesion capacity was 4.41 cells per cell, and the cell adhesion of F. nucleatum and S. mutans diminished strongly in protection and displacement assays. L. gasseri HHuMIN D was evaluated for safety using ammonia and biogenic amine development, hemolytic property and mucin degradation testing, antibiotic susceptibility, and whole genome sequencing (WGS).
Conclusion
Our results suggest that L. gasseri HHuMIN D may be a safe, bioactive, lactobacterial food ingredient, starter culture, and/or probiotic microorganism for human oral health.