A novel lipase as aquafeed additive for warm-water aquaculture

Abstract

A novel Acinetobacter lipase gene lipG1 was cloned from DNA extracted from intestinal sample of common carp (Cyprinus carpio), and expressed in E. coli BL21. The encoded protein was 406 amino acids in length. Phylogenetic analysis indicated that LipG1 and its relatives comprised a novel group of true lipases produced by Gram-negative bacteria. LipG1 showed maximal activity at 40°C and pH 8.0 when ρNP decanoate (C10) was used as the substrate, and remained high activity between 20°C and 35°C. Activity of the lipase was promoted by Ca 2+ and MgCa 2+, and inhibited by ZnCa 2+ and CuCa 2+. Moreover, LipG1 is stable with proteases, most commercial detergents and organic solvents. Substrate specificity test indicated that LipG1 can hydrolyse ρNP esters with acyl chain length from C2 to C16, with preference for medium-chain ρNP esters (C8, C10). Lastly, LipG1 was evaluated as an aquafeed additive for juvenile common carp (Cyprinus carpio). Results showed that supplementation of LipG1 significantly improved the gut and heptaopancreas lipase activity of fish fed with palm oil diet. Consistently, improved feed conversion ratio and growth performance were recorded in the LipG1 feeding group, to levels comparable to the group of fish fed with soybean oil diet. Collectively, LipG1 exhibited good potential as an aquafeed additive enzyme, and deserves further characterization as the representative of a novel group of lipases. Copyright: