In Vitro Studies on the Interaction of Phytase with Trypsin and Amylase Extracted from Shrimp (Penaeus vannamei) Hepatopancreas

Phytases are added to livestock feeds to enhance bioavailability of phytate phosphorus. The possibility of adding phytase to shrimp feeds was investigated by studying the in vitro interaction of phytase on trypsin and amylase extracted from the hepatopancreas (HP extract) of Penaeus vannamei . Proteolysis of soybean meal (SBM) protein measured as tryptic activity increased linearly with increasing phytase units, indicating that phytase may exert an indirect but positive effect on SBM protein hydrolysis. Increase in tryptic hydrolysis was not significantly affected by changes in pH from 5.5 to 8.5. An additive effect was observed between trypsin and possibly other proteolytic enzymes in the HP extract and phytase on the release of phosphorus from phytate in SBM. An inhibitory effect on HP extract amylase activity by phytase, reported here for the first time, may have important implications on direct addition of phytase to shrimp feeds.