Effects of Temperature and pH on Activities of Digestive Enzymes in Penaeus vannamei

The effects of different temperature and pH on activities of three digestive enzymes in Penaeus vannamei were examined.In stomach,hepatopancreas and intestine,the optimal temperature for lipase were 50,30,40 ℃,respectively and for amylase were all 30 ℃.In stomach,hepatopancreas and intestine,the optimal pH for protease were 6.0,6.0,7.0,respectively at water temperature of 40 ℃,that for amylase were 6.0,7.0,6.5,and that for lipase were all 7.0.The results indicated that protease was conductive to weak acidic condition in stomach and hepatopancreas and to weak alkaline condition in intestine,lipase was conductive to neutral condition and amylase to acidic condition.The activities of lipase and amylase increased,then decreased within the test temperature or pH range.