Effects of spray drying of L. rhamnosus 64 on its functional capacity in the small and large intestine of mice

BURNS, P.; REINHEIMER, J.; PÁEZ, R; VINDEROLA G; LAVARI, L.; TAVELLA, A.

Simposio; V International Symposium on Lactic Acid Bacteria; 2016

Spray drying is a dehydration technology used in the food and pharmaceutical industry for the development of numerous ingredients. When applied to microorganisms, it can be a low cost alternative to freeze-drying for strains able to survive this harsh process. Lactobacillus rhamnosus 64 is a strain isolated from feces of healthy infants that displayed probiotic potential according to previous studies, as well as satisfactory tolerance to spray drying in cheese whey-starch solution. The aim of this work was to study the effects of spray drying on the immunomodulatory profile induced in the gut by L. rhamnosus 64. BALB/c mice received (gavage) during 3, 6 or 10 consecutive days, 108 CFU of the strain as fresh culture (FC) or as a spray-dried (inlet T: 140°C, outlet T: 80°C, feeding 6 mL/min, mini spray dryer Buchi B-290) culture (SD) in 20% (w/v) cheese whey-starch. Phagocytic activity of peritoneal macrophages, the number of IgA-producing cells in the small and large intestine (immunohistochemistry), secretory- IgA in the luminal content of the small intestine (ELISA) and cytokine expression (IL-2, IL- 6, IL-10, IFN-γ and TNF-α) in homogenates of the small and large intestines (ELISA) were determined. The protective capacity against Salmonella enterica serovar. Typhimurium infection and against TNBS-induced acute colitis was assessed as well. An increase in phagocytic activity was observed after 3 days of administration of the strain, without differences between FC and SD. Different profiles in S-IgA were observed between FC and SD, but not in the number of IgA-producing cells. No changes in the expression of IL-2, IL-6 and IL-10 were observed in the small intestine, but an increase in IFN-γ and a decrease in TNF-α production were observed, without major differences between FC and SD. In the large intestine, no changes were observed for the expression of IL-2 and IL- 6. Both IFN-γ and TNF-α expression decreased in the large intestine, without differences between FC an SD. For IL-10, an increased on its expression was observed for FC for all feeding periods, but only for 3 d of administration for the SD. The strain was not effective on the protection against Salmonella infection, but it conferred partial protection against TNBS-induced colitis, only when it was administered as SD culture. The difference in effectiveness between FC and SD might be due to the extra charge of non-viable cells present in the SD culture, as result of a small lost in cell viability (less than 0.5 log orders) during spray drying. We conclude that L. rhamnosus 64 still displays functional properties after spray-drying in cheese whey-starch, although some functional traits might be affected by dehydration. These results show that the in vivo functionality of a probiotic candidate might be affected by the technological treatment applied for its production.