P19-20 : Ecological Control: Lactobacillus strains Interfere the Growth of a Periodontal Pathogen

Jaffar Norzawani¹,Maeda Toshinari¹,Mizuno Kouhei²,Okinaga Toshinari³
1Dept. Biol. Functions Eng., Kyushu Inst. Technol., 2Dept. Materials Sci. Chem. Eng., Kitakyushu Natl. College of Technol., 3Div. Infect. Mol. Biol., Kyushu Dent. Univ.
The oral ecology constitutes of several species of Lactobacillus and periodontal bacteria which are opportunistic to cause oral disease. Imbalance in the number of these bacterial groups was reported as one of the factors leading to a problem of oral health. Lactobacillus spp. contribute to acidic environment to oral cavity via the production of lactic acid and acetic acid, whereas a periodontal pathogen such as Aggregatibacter actinomycetecomitans requires neutral to alkaline conditions to grow optimally. The purpose of this study is to investigate whether metabolites of Lactobacillus spp. are able to inhibit the growth of A. actinomycetemcomitans via co-culture method and the numbers of each microorganism were determined using qRT-PCR. The production of lactic and acetic acid from Lactobacillus spp. and pH was measured to identify the influence of this metabolites and acidic condition towards the growth of A. actinomycetemcomitans. The number of A. actinomycetemcomitans after being co-cultured with a Lactobacillus strain was reduced in the range of 0.68 to 2.59 log copy DNA. An acidic condition in the co-culture medium shows growth inhibition of A. actinomycetecomitans; however, lactic acid from Lactobacillus spp. supports the growth of this bacterium in co-culture. In conclusion, it seems plausible that the inhibition was due to acidic condition but other than lactic acid

keywords:co-culture,lactic acid,,,