EFECT OF DIFFERENT CULTURE MEDIA AND THEIR COMPONENTS ON THE GROWTH OF BIOFILM-FORMING VAGINAL LACTOBACILLI

MARIA CECILIA LECCESE TERRAF; MARIA SILVINA JUAREZ TOMAS; MARIA ELENA FÁTIMA NADER; CLARA SILVA

SAN MIGUEL DE TUCUMAN

Congreso; VII CONGRESO ARGENTINO DE MICROBIOLOGIA GENERAL ?SAMIGE del BICENTENARIO?; 2011

The vaginal microbiota of healthy women is composed by different species of lactobacilli, which form a protective biofilm on the mucosa. These bacteria have a beneficial effect by inhibiting the adhesion, growth or spread of undesirable microorganisms. In urogenital infections, indigenous lactobacilli are replaced by pathogenic microorganisms, some of them form biofilms. Probiotic lactobacilli could displace this pathogenic biofilms and potentially reestablish those protective biofilms. Different human vaginal lactobacilli (VL) have been previously isolated, characterized and selected for their beneficial properties in our research group (autoaggregation, inhibition of uropathogens by organic acids, hydrogen peroxide and bacteriocins). Eventhough these microorganisms are very exigent nutritionally to grow, they were able to form biofilm in culture media without Tween 80 (a source of fatty acids) in ?in vitro? assays. Therefore, the objective of this work was to know if different culture media exert some effect on the growth of VL with different biofilm formation characteristics. Three biofilm-forming strains (Lactobacillus reuteri CRL1324, L. rhamnosus CRL1332 and L. delbrueckii CRL1510) and one non-biofilm-forming strain (L. gasseri CRL1263) were evaluated. The growth of the microorganisms was studied in LAPTg and MRS broths, with and without Tween 80. Growth kinetics were evaluated through optical densities (OD) at 540 nm, number of viable cells and pH. The strains tested showed a different behaviour under the different culture conditions assayed. L. rhamnosus CRL1332 was able to grow in the media with and without Tween (MRS and MRS without Tween OD=1.5; LAPTg and LAPTg without Tween OD=1). The growth of L. rhamnosus CRL1332 and L. reuteri CRL1324 was higher in MRS (OD=1.4-1.5) than in LAPTg (OD=1-1.1). L. reuteri CRL1324 growth was higher in complete media than in MRS and LAPTg without Tween (OD=1 and 0.75 respectively). L. delbrueckii CRL1510 growth was higher in standard media (OD=1.4) than in media without Tween (OD=0.82-0.88). L. gasseri CRL1263 growth was slightly higher in MRS (OD=1.4) than in LAPTg (OD=1.3), but did not grow in the media without Tween (OD=0.2). The pH decrease according to the growth in all the experiments (3.9-5.7).The different culture media assayed, used routinely for the growth of lactic acid bacteria, affect the growth kinetics of the evaluated microorganisms, showing a strain-specific response. Only the three strains previously selected for their ability to form biofilm in culture media without Tween 80, were able to grow under these conditions. However, the presence of Tween 80 in the culture media was essential for the growth of L. gasseri CRL1263. Further studies are being performed to determine the effect of the individual components of the culture media on both, the growth and biofilm formation of these microorganisms.