Recently, the increase of antimicrobial-resistant bacteria and the limitations of chemical agents in the treatment of disease have focused the attention to the utility of probiotics to suppress periodontal pathogens and normalize the oral microbiota. Though there are clinical research reports regarding the suppression of periodontal pathogens, establishment of probiotics remains difficult. With the objective to apply biogenics, the active constituent produced by probiotics, to prevention and treatment, we compared its antimicrobial effect against periodontal pathogens and analyzed the antimicrobial constituents.
A total of 49 Lactobacillus strains derived from human oral cavity and food were used as test bacteria. Each bacterial strain was grown in MRS broth for 24-48 hours under anaerobic condition and the centrifuged supernatant, adjusted to pH 7, used as a test sample. Antimicrobial activity againstPorphyromonas gingivalis (ATCC33277) was assessed under anaerobic condition for 48 hours. For purification of the antimicrobial constituent, a test sample was separated by chromatography gel filtration and further fractionated by C18 reversed-phase HPLC.
Among the 49 strains, 2 strains, L. plantarum122 (LP122) and L. fermentum ALAL020 (LF020) showed strong antimicrobial activity. The result of each antimicrobial constituent’s fractionation indicated a strong contribution of LP122 lactic acid to the antimicrobial effect. In case of strain LF020 a peptide with a molecular weight at least below 5kDa showed antimicrobial effect. A low molecular peptide produced by L. fermentum with antimicrobial effect has not been reported. This suggests the possibility of a new antimicrobial substance.
The active antimicrobial constituent of L. fermentum against P. gingivalis is a low molecular peptide, suggesting the possibility of a new substance.