Effects of probiotic and pharmaceutical substances on the viability of freeze-dried vaginal lactobacilli during storage

SARALEGUI DUHART, MC; JUAREZ TOMAS, MARIA SILVINA; MARIA ELENA FÁTIMA NADER

Córdoba, Argentina

Congreso; V Congreso Argentino de SAMIGE; 2007

AAM

Effects of prebiotic and pharmaceutical substances on the viability of freeze-dried vaginal lactobacilli during storage Carolina I. Saralegui Duhart1, María S. Juárez Tomás1, María E. Nader-Macías1 Centro de Referencia para Lactobacilos (CERELA)?CONICET. Chacabuco 145. San Miguel de Tucumán. 4000. Argentina. Lactobacilli are widely applied as probiotic microorganisms to restore the ecological balance of different animal or human tracts, and to produce a physiological effect in the host. They contribute to the reestablishment of the indigenous vaginal microflora preventing the adhesion or the growth of uropathogenic microorganisms, or stimulating the immune system. To design a probiotic product to restore and maintain the indigenous vaginal flora, both functional and technological properties of the potentially probiotic strains must be well determined. Maximum survival of probiotic microorganisms during the industrial processes of biomass production and storage is of vital importance. The objective of the present study was to determine the effects of lyoprotectors on the survival of four potentially probiotic vaginal lactobacilli during the freeze-drying process and their subsequent storage in presence of prebiotic or pharmaceutical substances. <i>Lactobacillus</i> spp. CRL 1263, <i>Lactobacillus</i> spp. CRL 1251, <i>Lactobacillus</i> spp. CRL 1294 and <i>L. salivarius</i> CRL 1328 were subcultured under optimal growth conditions at 37°C three times, and the last culture harvested in stationary phase. The cell pellets were washed twice with distilled water, and re-suspended in each one of the following protective medium: 10% whey protein concentrate (WPC) or 6% reconstituted skim milk added with 12% lactose (RSM/lactose). Bacterial suspensions were freeze-dried, the lyophilized powders were combined with inulin, ascorbic acid or asiatic centella extract, the resulting mixtures were placed into gelatin capsules and stored at 7°C. Viable counts of vaginal lactobacilli were determined before and after freeze-drying, and at different times throughout 60 days of storage, by employing the plate dilution method. The degree of survival was expressed in log CFU/g (colony forming units per g of freeze-dried powder). For most of the microorganisms, losses of viability during freeze-drying were not significant in presence of the two lyoprotectors evaluated, except for <i>L. salivarius</i> CRL 1328 (2 log down in RSM/lactose). Viability of microorganisms during storage was affected at different extents depending on lyoprotectors, storage time and substances added to the freeze-dried powders. As a general result, maximum survival up to 60 days was observed with WPC and RSM/lactose, supplemented with either inulin or asiatic centella for all the strains. The results of this work indicate that both lyoprotectors tested were effective in protecting the microorganism during the freeze-drying process and subsequent storage. Among the substances added after lyophlization process, only ascorbic acid not favored the survival of the cells during storage in gelatin capsules. These findings help in the design of a pharmaceutical product containing probiotic microorganisms for the prevention of urogenital infections, which is the final objective of our research group.