Bovine vaginal Lactobacillus acidophilus produces H2O2 and inhibits Staphylococcus aureus

M.C. OTERO; M.E. NADER-MACÍAS

Italia

Congreso; 2º Probiotics, Prebiotics & New Foods; 2003

Idea Congress SRL

BOVINE VAGINAL Lactobacillus acidophilus PRODUCES H2O2 AND INHIBITS Staphylococcus aureus. María Claudia Otero and María Elena Nader-Macías.  The hydrogen peroxide-positive Lactobacillus participate in the stability and equilibrium of the vaginal microbiota. Our research is directed to the selection of beneficial Lactobacillus for probiotic use in the bovine vaginal tract, to prevent the uncontrolled bacterial colonization causing metritis in the postpartum. L. acidophilus CRL 1421, H202 producer, was assayed with Staphylococcus aureus in LAPTg broth at 37°C under static and agitated conditions. The number of microorganisms was determined in MSA (S. aureus) and MRS agar (Lactobacillus), measuring pH and H2O2 during the growth. The damage of S. aureus cells was evaluated by transmission electron microscopy. In the L. acidophilus CRL 1421 cultures, aeration increased the growth rate and H2O2 production, but the final biomass decreased. The final pH of aerated cultures was 0,46 pH units higher than in static cultures. The Minimal Inhibitory Concentration of H2O2 on S. aureus was 1.65 mmol l-1. In the mixed cultures, the growth of S. aureus was inhibited after 3 h. of incubation, but after 24 h. 102 cells ml-1 remained viable. Under aerated conditions, the inhibition was observed from the beginning of the growth, and a complete inhibition was obtained before 24 h. The inhibitory effect was partially reverted when catalase was added, being evident from 6h. of incubation. The Lactobacilli supernatant produced a strong damage in the S. aureus cell structure, observing disintegration and loss on the cell wall, which agrees with the decreased viability of the staphylococci cells in Lactobacilli supernatants. Conclusion: The L. acidophilus 2014 inhibits a bovine potentially pathogen by the production of antagonistic substances, suggesting the application for probiotic purposes. This strain could be combined with other probiotic strains to be used in the restoration of the vaginal microflora of cows during postpartum .