The effects of temperature and pH on activities of digestive enzymes in jade perch(Scortum barcoo) in Australia

The effect of different temperature and pH on activities of three digestive enzymes in jade perch Scortum barcoo were examed.The optimum pH value for amylase in liver,intestine and the stomach were all 6.2 at water temperature of 25℃.The optimum pH value for protease of liver,intestine were all 7.0-7.5,and 2.0 and 6.5 in stomach at water temperature of 40℃.The results indicated that amylase was conductive to weak acidic condition,and protease in liver and intestine were conductive to weak alkaline condition while the protease in stomach was conductive to acidic condition.The optimum temperature in amylase of the liver,intestine and stomach were all 30℃ when the reaction pH value was 6.9. The optimum temperature for protease were 50,50,40℃ and for lipase were 40,35,35℃ respectively pH value of 7.5.The results indicated that the optimum temperature of the three digestive enzymes in liver,intestine and stomach were higher than the temperature for growth.The activities of amylase,lipase and protease increased,then decreased within the test temperature range.All the activity of three digestive enzymes was in an order of from strong to weak: intestine,liver,and stomach at the most favorable temperature.