Thermal and pH stability of lipases from Etroplus suratensis (Pearl spot) and Oreochromis mossambicus (Tilapia):
A comparative study
Keywords:Digestive enzymes; Temperature; Kinetics; Cichlids; Physiology
Lipases of marine origin are enzymes less studied than those from other organisms. Etroplus suratensis (Pearlspot) and Oreochromis mossambicus (Tilapia) are potential euryhaline aquaculture species. Intestinal lipase (IL) from E. suratensis was found to be stable up to 35°C, beyond which thermal inactivation occurs. The IL of O. mossambicus remained stable at temperatures lower than 50°C with an optimum of 45°C. Extensive differences in pH stability of lipases from these two fishes were observed. Tilapia lipase exhibited 70-80% relative activity in broad pH range (4.5-10.5). However, E. suratensis lipase was found to be more stable in acidic and neutral pH (3.5-7) than alkaline (7.5-10.5). Specific pH optimum was exhibited by Tilapia IL (pH 9) while Pearlspot displayed a pH range (8.5 to 9.5). The O. mossambicus can hydrolyze lipids in a wide range of temperature and pH and it can be used in various food and industrial applications.