Methods: The inhibitory activity of various oral Lactobacillus spp. against putative oral pathogens has been performed. Lactobacillus paracasei SD1 was selected as the most active strain for further investigation. The antimicrobial proteins were extracted from culture supernatant of L. paracasei SD1 and were precipitated with ammonium sulfate. Antimicrobial activity was performed using methods of broth microdilution and agar overlay of native-polyacrylamide gel electrophoresis.
Results: Among Lactobacillus strains tested, L. paracasei was the most active strains in inhibiting growth of periodontal pathogens. The further study demonstrated that L. paracasei SD1 presented antimicrobial proteins against Aggregatibacter actinomycetemcomitans ATCC 33384 with the molecular weight of approximately 49.1 KDa. The minimum inhibitory concentration (MIC) value of protein against A. actinomycetemcomitans was 5.52 µg/ml.
Conclusions: Antimicrobial protein from L. paracasei SD1 had the ability to inhibit growth of A. actinomycetemcomitans, suggesting that there may be promising alternative chemotherapeutic agents for prevention of periodontal diseases.
This work was supported by the Higher Education Research Promotion and National Research University project of Thailand Office of the Higher Education Commission (AGR 540555M ), the National Science and Technology Development Agency (NSTDA) of Thailand and the National Research Council of Thailand.