Role of Peptidases of the Enteric Microbiota and Prey in Temperature Adaptations of the Digestive System in Boreal Carnivorous Fish

For the first time the activity of casein-lytic and hemoglobin-lytic peptidases of intestinal mucosa, chyme and enteric microflora of carnivorous boreal fish (pike, zander, burbot, perch) was investigated across a wide temperature range (0-70 degrees C) to reveal the role of the enzymes of the enteric microbiota and the prey in the temperature adaptations of the digestive system of these fish. It was shown that in summer at 0 degrees C, the relative activity of peptidases of intestinal mucosa (less than 20%) is usually considerably less than that of chyme and enteric microflora peptidases (up to 40% of maximal activity). In winter, on the background of low relative activity of mucosa and enteric microbiota peptidases at 0 degrees C revealed a high level of the relative activity of burbot and pike chyme peptidases (45 and 80% of maximal activity). The role of enteric microbiota and prey peptidases in digestive system adaptations of piscivorous fish to low temperatures is discussed.