Lactobacilli isolated from kefir increase their adhesion capacity to intestinal mucosa in vitro after simulated digestion

ZAVALA, LUCÍA; CARASI PAULA; SERRADELL MARÍA DE LOS ANGELES; ABRAHAM A.

Rosario, Argentina

Congreso; IX Congreso Argentino de Microbiología General; 2013

SAMIGE

Kefir is a probiotic beverage obtained through fermentation of milk with ?kefir grains?. Kefir grains are constituted by a complex symbiotic microbiota, which includes Lactobacillus kefir and Lactobacillus paracasei. The resistance to artificial gastric and intestinal juices and the adhesion capacity to the intestinal mucosa are some of the factors involved in the selection criteria for a potentially successful probiotics. The aims of this study were to evaluate the resistance of different L. kefir and L. paracasei strains to simulated gastric and intestinal fluids and to analyze it?s the effect on bacterial binding capacity to mucin and Caco-2/TC7 cell line. In this study, eight L. kefir strains (CIDCA 8321, 8345, 8348, 83102, 83111, 83113, 83115 y JCM 5818) and five L. paracasei strains (CIDCA 8339, 83120, 83121, 83123, 83124) were used. Initially, bacterial binding capacity to mucin and Caco-2/TC7 cell line was evaluated. Viability of bacterial suspensions incubated sequentially in solutions simulating the gastric (pepsin, pH 2, 90 minutes) and intestinal (pancreatin and bovine bile salts, pH 8, 180 minutes) compartments was assessed. According to these results, different strains were selected and adhesion assays to mucin and epithelial cells were performed after simulation of gastrointestinal tract´s passage. Strains were grouped according to their resistance to gastrointestinal conditions. All L. kefir strains showed the same resistance rates to simulated gastric and intestinal fluids, (viable microorganisms decreased 2 logs). In the case of L. paracasei strains, CIDCA 8339 was the most resistant (similar to L. kefir strains) meanwhile L. paracasei CIDCA 83121 and CIDCA 83124 were very sensitive to this treatment, decreasing counting at least 4 logs. For all the bacterial strains under study, the critical step was the incubation in simulated gastric juice. Regarding adhesion properties, L. kefir and L. paracasei strains adhered 9.5x104 ? 1x106 CFU/cm2 to mucin (9x107 CFU/cm2 were initially inoculated) and 1.5 ? 5 CFU/cell to Caco-2/TC7 cells (100 CFU/cell were initially inoculated) before treatment. Gastrointestinal tract´s passage simulation significantly increased adhesion to mucin of selected strains: L. kefir (CIDCA 8348, 83102, 83115 y JCM 5818) and L. paracasei (CIDCA 8339, 83123, 83124). However, adhesion capacity to Caco-2/TC7 cells was increased only for L. kefir CIDCA 8348, 83102 and 83115 and L. paracasei CIDCA 83123 and 83124. A greater variability in behavior was observed between L. paracasei strains than that of L. kefir strains. Simulated gastrointestinal tract´s passage modificated bacterial surface and these modifications changed adhesion rates to mucin and Caco-2/TC7 cells. Based on these results, we considere that L. kefir CIDCA 8348, 83102 and 83115 and L. paracasei CIDCA 83123 are excelent candidates for the development of probiotic products.