COMPARATIVE-STUDY OF PROTEOLYTIC-ENZYMES IN THE DIGESTIVE TRACTS OF THE EUROPEAN SEA BASS AND HYBRID STRIPED BASS REARED IN FRESH-WATER

1. A comparative study of the proteolytic activity in four different sections of the digestive tracts of the European sea bass (Dicentrarchus labrax) and hybrid striped bass (Morone chrysops x M. saxatilis) reared in freshwater revealed minor differences between these fish. 2. Tryptic activity plays a major role in the proteolytic process in both fish. 3. The activity of seven intestinal proteolytic enzymes was detected utilizing a combination of specific substrates and inhibitors. 4. High levels of proteolytic activity were detected in both the proximal and distal sections of the fish intestine at a high pH range (9-10). 5. In situ monitoring of pH levels revealed a lower pH level in the intestinal proximal section of hybrid striped bass compared with the distal section. 6. In contrast, higher pH levels were detected at the proximal compared with the distal sections of D. labrax intestine.