The Probiotic Strain Hafnia Alvei HA4597 and Its Protein Extract Selectively Activate Membrane Digestive Enzymes of Intestinal Cells in Mice

Oral supplementation of the Hafnia alvei (H. alvei) HA4597 probiotic strain has been shown to reduce appetite, body weight and fat content in overweight humans and obese mice. However, it remains unknown if H. alvei may also influence the gut digestive function. Thus, in the present study, the structural parameters of the intestine and the activity of digestive enzymes of the brush border enterocytes were analyzed in mice after they received a suspension of live H. alvei bacteria or their total protein extract for 16 days. Using electron microscopy, bacteria resembling H. alvei were found on the surface of microvilli of colonic enterocytes of mice treated with H. alvei suspension. In the group receiving H. alvei protein, there was a trend toward an increase in the number of mucus-producing goblet cells on the villi of the jejunum, and in both groups receiving H. alvei preparations, the number of intraepithelial lymphocytes on the villi of the ileum increased (in the group receiving H. alvei protein, there was a tendency towards an increase; in the group receiving H. alvei suspension, there was a significant increase). Treatment with both H. alvei preparations led to an increased activity of alkaline phosphatase in the chyme of the duodenum and jejunum and also in the jejunal mucosa, correlating negatively with visceral body fat content. The use of both H. alvei preparations had no significant effect on the activity of glucoamylase, maltase and aminopeptidase N in the intestinal mucosa. Thus, the 16-day administration of H. alvei bacteria or their protein extract increases the protective properties of the intestine, including the mucous barrier. Moreover, increased activity of alkaline phosphatase, a fat absorption-limiting enzyme, may contribute to the known anti-obesity effects of H. alvei. Taken together, H. alvei preparations display beneficial effects on gut health.