Lactobacillus acidophilus-derived biosurfactant effect on gtfB and gtfC expression level in Streptococcus mutans biofilm cells

Streptococcus mutans (S. mutans), harboring biofilm formation, considered as a main aetiological factor of dental caries. Gtf genes play an important role in S. mutans biofilm formation. The purpose of this study was to investigate the effect of Lactobacillus acidophilus-derived biosurfactant on S. mutans biofilm formation and gtfB/C expression level (S. mutans standard strain ATCC35668 and isolated S. mutans strain (22) from dental plaque). The Lactobacillus acidophilus (L. acidophilus) DSM 20079 was selected as a probiotic strain to produce biosurfactant. The FTIR analysis of its biosurfactant showed that it appears to have a protein-like component. Due to the release of such biosurfactants, L. acidophilus was able to interfere in the adhesion and biofilm formation of the S. mutans to glass slide. It also could make streptococcal chains shorter. Using realtime RT-PCR quantitation method made it clear that gtfB and gtfC gene expression were decreased in the presence of L. acidophilus-derived biosurfactant fraction. Several properties of S. mutans cells (the surface properties, biofilm formation, adhesion ability and gene expression) were changed after L. acidophilus-derived biosurfactant treatment. It is also concluded that biosurfacant treatment can provide an optional way to control biofilm development. On the basis of our findings, we can suggest that the prepared biosurfactant may interfere with adhesion processes of S. mutans to teeth surfaces, provided additional evaluation produce satisfactory results.

The effect of a probiotic strain (Lactobacillus acidophilus) on the plaque formation of oral Streptococci.

The objective of this study was to investigate the ability of biofilm formation among mutans and non mutans oral streptococci and to determine the effect of Lactobacillus acidophilus DSM 20079 as a probiotic strain on the adhesion of selected streptococcal strains on the surfaces. The sample comprised 40 isolates of oral streptococci from dental plaque and caries of volunteer persons. Streptococcus mutans ATCC35668 (no24) was as an standard strain. The probiotic strain was Lactobacillus acidophilus DSM 20079. The ability of biofilm formation was investigated with colorimetric method and the strongest isolates were selected. Then the effect of probiotic strain on the adhesion of streptococci isolates was determined in polystyrene microtiter plate simultaneously and 30 minutes before streptococci entrance to the system. The results showed that 42% of mutans streptococci were strongly adherent (SA) and in non mutans streptococci, only 23.5% of isolates were found strongly adherent. The strong biofilm forming bacterium isolated was Streptococcus mutans strain22. In the next step, in the presence of probiotic strain the streptococcal adhesion were reduced, and this reduction was non significantly stronger if the probiotic strain was inoculated to the system before the oral bacteria. The Lactobacillus acidophilus had more effect on adherence of mutans streptococci than non mutans streptococci with significant difference (p < 0.05). Adhesion reduction is likely due to bacterial interactions and colonization of adhesion sites with probiotic strain before the presence of streptococci. Adhesion reduction can be an effective way on decreasing cariogenic potential of oral streptococci.

Assessment of bile salt effects on s-layer production, slp gene expression and some physicochemical properties of Lactobacillus acidophilus ATCC 4356.

In many conditions, bacterial surface properties are changed as a result of variation in growth medium and conditions. This study examined the influence of bile salt concentrations (0-0.1%) on colony morphotype, hydrophobicity, H2O2 concentration, S-layer protein production and slpA gene expression in Lactobacillus acidophilus ATCC 4356. It was observed that two types of colonies (R and S) were in the control group and the stress condition. When the bile level increased in the medium, the amount of S type was more than the R. A stepwise increment in the bile concentration resulted in a stepwise decline in the maximum growth rate. The results showed that hydrophobicity was increased in 0.01%-0.02% bile but it was decreased in 0.1% bile. Treatment by bile (0.01%- 0.1%) profoundly decreased H2O2 formation. S-layer protein and slpA gene expression was also altered by stress condition. S-protein expression was increased in stress condition. slpA gene expression increased in 0.01%-0.05% bile and it decreased in 0.1% bile. However, we found that different of bile salt concentrations influence on morphology and some surface properties of L. acidophilus ATCC 4356. These changes were very different in the 0.1% bile. It appears that the bacteria respond abruptly to 0.1% bile.