Comparison of the growth and hydrogen peroxide production by vaginal probiotic lactobacilli under different culture conditions.

Objective: The purpose of this study was to determine the optimal conditions for the growth and hydrogen peroxide production by vaginal lactobacilli.

Study Design: Two vaginal lactobacillus strains were cultured under different growth conditions (temperature, pH, agitation, and growth media) with a fractional factorial experimental design.

Results: The optimal growth conditions of Lactobacillus paracasei CRL (Centro de Referencia para Lactobacilus Culture Collection) 1289 and Lactobacillus crispatus CRL 1266 were temperature 37 degrees C and initial pH 6.5, nonagitated cultures, in autolysat de levure; peptone, tryptone, Tween 80 et glucose (LAPTg) broth for L paracasei or in de Man-Rogosa-Sharpe (MRS) and LAPTg broths for L crispatus. The hydrogen peroxide production, detected only in agitated cultures, was higher at 37 degrees C and pH 6.5. The oxidative metabolite produced the self-inhibition of the lactobacilli growth. In mixed cultures of lactobacilli and Staphylococcus aureus under the optimal conditions of hydrogen peroxide production, the pathogen growth was inhibited.

Conclusion: The results provided information about the factors that affect the hydrogen peroxide production and about the most favorable conditions with which to obtain the highest biomass in the shortest possible time.