PH values and activity of digestive enzymes in the gastrointestinal tract of fish in Lake Chany (West Siberia)

Abstract

Optimum pH of various digestive enzymes and physiological pH values were determined in the gastrointestinal tract of fish species, such as goldfish Carassius auratus gibelio, ide Leuciscus idus, wild carp Cyprinus carpio, perch Perca fluviatilis, and zander Sander lucioperca. Physiological values of pH in the stomach of perch and zander and in different parts of the intestine of all studied fish species range within 3.5–4.5 and 6.5–7.2, respectively. The maximum values of the activity of alkaline protease and nonspecific lipase and esterase are recorded at pH 8–9; the maximum acid protease activity is recorded at pH 2–3. The optimum pH activity of alkaline protease and nonspecific lipase and esterase do not correlate with actual pH value in the digestive tract of fish. Two peaks of α-amylase activity are observed at pH 7 and 9.