Viability and β-Galactosidase Activity of Dairy Propionibacteria Subjected to Digestion by Artificial Gastric and Intestinal Fluids

Abstract

An important criterion to consider in the selection of strains for dietary adjuncts is the ability of the microorganisms to survive the severe conditions of acidity and bile concentrations usually found in the gastrointestinal tract. In the present work, we report the effects of digestions by artificial gastric and intestinal fluids on beta-galactosidase activity and survival of four strains of dairy propionibacteria previously selected by their bile tolerance and beta-galactosidase activity. The strains were exposed to artificial gastric juice at pH values between 2 and 7 and then subjected to artificial intestinal digestion. Both viability and beta-galactosidase activity were seriously affected at pH 2. Skim milk and Emmental cheese juice exerted a protective effect on the parameters tested. The trypsin present in the intestinal fluid inactivated the enzyme beta-galactosidase in strains of Propionibacterium freudenreichii but not in Propionibacterium acidipropionici. Moreover, the presence of bile salts enhanced the beta-galactosidase activity of these strains by permeabilization of the cells during the first hour of exposure. The intestinal transit rate confirmed the permanence of the bacteria in the intestine for long enough to be permeabilized. These results suggest that P. acidipropionici would be a good source of beta-galactosidase activity in the intestine. We also propose a practical and effective in vitro method as a tool of screening and selection of potential probiotic bacteria.

Dairy Propionibacteria: Less Conventional Probiotics to Improve the Human and Animal Health

“…It has also been demonstrated that the vehicle used for delivery of probiotics is important for digestive stress tolerance since cells included in food matrices like milk or cheese had better tolerance to acid challenge than free cultures [132]. Similar results were obtained by Huang and Adams [134], by protecting propionibacteria from acid and bile stresses with a soymilk and cereal beverage, and Leverrier et al [136], who used yoghurt-type fermented milk.…”

“…However there are no clinical reports on this property for dairy propionibacteria. Several evidences suggest the potential of Propionibacterium acidipropionici strains on this subject: they have high β-galactosidase activity that remain unaltered in the conditions of the human's intestine, and cells are permeabilized by bile, which in turn may favour the hydrolysis of lactose within the intestine [131,132]. Besides, the manufacture conditions of Swiss-type cheese did not decrease the synthesis and activity of the β-galactosidase of these propionibacteria [197].…”

“…In previous studies [131,132] we observed that dairy propionibacteira developed in a medium containing bile (0 -0.5%) behaved as "bile-tolerant" and "non bile-tolerant" strains and that there were differences among P. freudenreichii and P. acidipropionici strains in their tolerance to pancreatic enzymes when subjected to sequential digestion with artificial gastric and intestinal fluids.…”

“…Many studies have demonstrated by in vitro assays the ability of dairy propionibacteria to survive and tolerate the gastrointestinal conditions [130][131][132][133][134]. This tolerance could be improved by a pre-adaptation of the microorganisms to the adverse conditions of the gut by a brief exposure to the stressful conditions at a non-lethal level [48,135].…”

Survival and beneficial effects of propionibacteria in the human gut: in vivo and in vitro investigations

“…Furthermore, they were able to down-regulate the carcinogenic β-glucuronidase, azoreductase and nitroreductase activities in these animals [23]. Propionibacteria were also shown to be a source of β-galactosidase, which would be liberated as a result of bile salts permeabilisation within the gut [32]. They could thus be useful to prevent lactose intolerance.…”