Antimicrobial Activity of Probiotic Strain Grown in Edible Media

Objectives: Our laboratory has isolated probiotic strain, Lactobacillus rhamnosus KO3 (L8020), from resting saliva of 13 subjects without caries experience, which reduced oral carriage of cariogenic bacteria, and periodontal pathogens through placebo controlled double blind test.
In this study, L8020 were cultured in the four types of edible media, and antibacterial activity against cariogenic bacteria and periodontal pathogens was examined in vitro.
Methods: As the medium sample, wheat-based liquid medium (wheat), sweet potato-based liquid medium (sweet potato), sweet potato liquid medium 2 (sweet potato 2), and sweet corn fine liquid medium (corn) were used. L8020 were cultured in each liquid medium at 37^oC for 24hours, then centrifuged at 3000rpm for 5min, and the supernatant of each culture was used for antimicrobial assay. Same volume of sterilized distilled water was used as control. Antimicrobial assay was carried according to our previous study (Nikawa H et al. J Invest Clin Dent 2, 187-196, 2011). Streptococcus mutans UA130 (S.m) and Porphyromonas gingivalis Hudoi (P.g) were used as the test strains. The number of remaining bacteria was measured by ATP measurement, and the survival rate of the bacteria was calculated. All the numerical data were analyzed by ANOVA and Tuckey’s multiple range test.
Results: Corn and sweet potato were well supported the growth of L8020, followed by sweet potato 2 and wheat showed the least. Sweet potato, sweet potato 2 and corn significantly suppressed the growth of S.m, and sweet potato 2 and corn suppressed the growth of P.g.
Conclusions: These results, taken together, suggested that L8020 grown in the edible media exhibited the antibacterial effect against cariogenic bacteria and periodontal pathogen.