Identification and Characterization of a Chitinase Activity in the Gut of the Yellow‐Bellied Slider Turtle Trachemys scripta

The Slider Turtle, Trachemys scripta, undergoes an ontogenetic dietary shift from a largely insect based diet to a plant based diet. Throughout the shift, the turtles must be able to access and utilize the maximum nutritional content available in both diets. Digestive enzymes such as endochitinase and exochitinase have been found throughout the gut that assist in nutrient breakdown. This work aimed to establish and characterize an endogenous chitinase in T. scripta. Activity was assayed using a chitin substrate tagged with fluorescent 4‐methylumbelliferone. Both endo‐ and exochitinase activity occurs within the stomach, small intestine, large intestine, and pancreas of T. scripta with optima occurring at pH 2.5 and 5; additionally, the activity at pH 2.5 was inhibited by 1M NaCl. These two peaks suggest that two enzymes work throughout the GI tract as the levels of pH change within each segment of the gut. This work was sponsored by the Merck AAAS Undergraduate Science Research Program.