Different combinations of salts affect the growth and bacteriocin production by vaginal Lactobacillus salivarius CRL 1328

MARIA SILVINA JUAREZ TOMAS; ELENA BRU; MARIA ELENA NADER-MACIAS

Nantes, Francia

Simposio; 1st International Symposium on Food, Veterinary and Medical applications of antimicrobial peptides.; 2006

ENITIAA-Nantes

Lactobacillus salivarius CRL 1328 or the bacteriocin produced could be included in a probiotic formula to prevent urogenital infections in women [1]. In previous studies, the optimal growth of vaginal L. salivarius was recorded in standard MRS, while the maximum bacteriocin activity was obtained in LAPTg [2]. In the present work, the effects of different salts on the growth and bacteriocin production of L. salivarius were evaluated. The study was performed by using a complete factorial experimental design 26. Sixty four different growth media resulting from the combinations of two base culture media (LAPTg and MRS without salts), and two concentrations of 5 salts (0 and 2 g/l ammonium citrate, 0 and 5 g/l sodium acetate, 0 and 0.1 g/l MgSO4, 0 and 0.05 g/l MnSO4, and 0 and 2 g/l K2HPO4) were assayed. The growth was determined by optical density (O.D. at 540 nm.), and the bacteriocin levels by the plate method assay [2]. Among the different salts tested, only the addition of 0.05 g/l Mn2+ to each base medium stimulated the growth of L. salivarius, reaching similar O.D. values to those obtained in standard MRS (1.3 at 12 h). The use of LAPTg as base culture medium, or the presence of sodium acetate or MgSO4 stimulated the bacteriocin production of L. salivarius (maximal values of 3.1 Log UA/ml), while MnSO4 and K2HPO4 exerted an inhibitory effect. However, the simultaneous addition of MnSO4 and sodium acetate to both base media allowed to reach high bacteriocin levels (around 2.85 Log UA/ml), attenuating the inhibitory effect of Mn2+. In conclusion, the carbon and nitrogen sources of LAPTg or MRS combined with different concentrations of several salts allowed to optimize simultaneously the production of biomass and bacteriocin of L. salivarius CRL 1328. The results obtained are potentially applicable to the technological production of probiotic bacteria and antagonistic substances. References 1.      Ocaña, V. S., A. P. de Ruiz Holgado, and M. E. Nader-Macías. 1999. Characterization of a bacteriocin-like substance produced by a vaginal Lactobacillus salivarius strain. Appl. Environ. Microbiol. 65:5631-5635. 2.      Juárez Tomás, M. S., E. Bru, B. Wiese, A. P. de Ruiz Holgado, and M. E. Nader-Macías. 2002. Influence of pH, temperature and culture media on the growth and bacteriocin production of vaginal Lactobacillus salivarius CRL 1328. J. Appl. Microbiol. 93:714-724.