Abstract
A novel Acinetobacter lipase gene lipG1was 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℃ and pH 8.0 when pNP decanoate (C10) was used as the substrate, and remained high activity between 20℃ and 35℃. Activity of the lipase was promoted by Ca2+ and Mg2+, and inhibited by Zn2+ and Cu2+. Moreover, LipG1 is stable with proteases, most commercial detergents and organic solvents. Substrate specificity test indicated that LipG1can hydrolyse pNP esters with acyl chain length from C2 to C16, with preference for medium-chain pNP esters (C8, C10). Lastly, LipG1was evaluated as an aquafeed additive for juvenile common carp (Cyprinus carpio). Results showed that supplementation of LipG1significantly 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.
Highlights
China is the largest aquaculture producer in the world, with a total production of 53.94 million tons of fish in 2012, accounting for nearly 60% of the world total [1]
A 20 amino acid residue signal peptide was found at the N-terminal of the lipase with a cleavage position between Cys20 and His21 as predicted by Signal P (Fig A in S2 File)
BLASTp analysis indicated that LipG1 was 99% identical to hypothetical protein from Acinetobacter tandoii (WP_016167430.1), and was 70%, 68%, 68%, 62% and 61% identical to lipases from A. baumannii 348935 (WP_034704719.1), Acinetobacter sp
Summary
China is the largest aquaculture producer in the world, with a total production of 53.94 million tons of fish in 2012, accounting for nearly 60% of the world total [1]. The price of aquafeed is relatively high, which represents one of the main bottlenecks for the development of aquaculture. Dietary lipids provide essential fatty acids and are important source of energy for fish. The optimum dietary lipid levels for tilapia and common carp are as high as 8% and12%, respectively [2]. Fish oil and soybean oil have been used as the lipid source in aquafeed for these fish species. Due to the high price of both fish oil and soybean oil, as well as the finite nature of fish oil, alternative vegetable oils are prevalent. PLOS ONE | DOI:10.1371/journal.pone.0132049 July 6, 2015
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
