Abstract
Kefir is a beverage obtained by fermentation of milk or sugar solution by lactic acid bacteria and yeasts, and several health benefits have been attributed to its ingestion, part of them being attributed to Lactobacillus species. The objective of the present study was to evaluate, in vivo, the probiotic potential of Lactobacillus diolivorans 1Z, isolated from Brazilian kefir grains. Initially, conventional mice were orally treated daily or not during 10 days with a suspension of L. diolivorans 1Z, and then orally challenged with Salmonella enterica serovar Typhimurium. Treatment with L. diolivorans 1Z resulted in higher survival (70%) of animals after the challenge with the pathogen than for not treated mice (0%). When germ-free mice were monoassociated (GN-PS group) or not (GN-CS group) with L. diolivorans 1Z and challenged after 7 days with S. Typhimurium, Salmonella fecal counts were significantly lower (P < 0.05) for the GN-PS group when compared to the GN-CS group. Histopathological analysis revealed less damage to the ileum mucosa, as demonstrated by smallest perimeter of major lesions for mice of the GN-PS group in comparison to the group GN-CS (P < 0.05). These findings were accompanied by a lower expression of IFN-γ and TNF-α in the intestinal tissue of GN-PS mice. Additionally, translocation of S. Typhimurium to liver was significantly lower in GN-PS than in GN-CS mice (P < 0.05), and IgA levels in intestinal content and number of Kupffer cells in liver were higher. No difference was observed for hepatic cellularity between GN-PS and GN-CS groups (P > 0.05), but the pattern of inflammatory cells present in the liver was predominantly of polymorphonuclear in GN-CS group and of mononuclear in the GN-PS group, and a higher hepatic expression of IL-10 and TGF-β was observed in GN-PS group. Concluding, L. diolivorans 1Z showed to be a potential probiotic strain that protected mice from death after challenge with S. Typhimurium, apparently by immunological modulation.
Highlights
Kefir is an acidic fermented beverage, lightly alcoholic, obtained through the double fermentation of milk or sugar solution (Garrote et al, 2010)
Lactobacillus diolivorans 1Z demonstrated to be resistant to gastric juice and bile salts, to produce antagonistic compounds against several pathogens, and showed an antimicrobial susceptibility pattern typical of Lactobacillus genus (Zanirati et al, 2015). These results suggest that L. diolivorans 1Z could survive to the passage through the intestinal tract, as expected for a probiotic strain (Ranadheera et al, 2012)
Higher survival (70%) and body weight gain were observed in animals that were previously treated with oral administration of L. diolivorans 1Z in comparison with animals receiving only water (0% survival) before the pathogenic challenge
Summary
Kefir is an acidic fermented beverage, lightly alcoholic, obtained through the double fermentation (alcoholic and acidic) of milk or sugar solution (Garrote et al, 2010). Beneficial effects associated with kefir intake have already been suggested in several studies and there are evidences that many of these effects are attributed to the Lactobacillus species (Vinderola et al, 2005; Zamberi et al, 2016; Iraporda et al, 2017; Sharifi et al, 2017) Due to their long history of use in food fermentation and absence of pathogenic factors, Lactobacillus are generally recognized as safe for consumption and have been exploited as probiotics, which are live microorganisms that, when administered in adequate amounts, confer a health benefit on the host (FAO/WHO, 2002). Salmonellosis is an acute infection with a worldwide distribution caused by serovars of Salmonella enterica subsp. Oral infection with S. enterica subsp. enterica serovar Typhimurium in mice provokes a disease similar to that caused by S. enterica serovar Typhi in humans, with fever, enteritis (without the acute diarrhea observed in humans), and septicemia which is lethal to the host (Santos, 2014)
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