title: High-yield production of a chitinase from Aeromonas veronii B565 as a potential feed supplement for warm-water aquaculture.
abstract: Chitin, present in crustacean shells, insects, and fungi, is the second most plentiful natural organic fiber after wood. To effectively use chitin in a cost-saving and environmentally friendly way in aquaculture, crustacean shells (e.g., shrimp-shell meal) are supplemented into aquafeed after degradation by chemical methods. Herein, we describe a chitinase from Aeromonas veronii B565, designated ChiB565, which potently degrades shrimp-shell chitin and resists proteolysis. We isolated recombinant ChiB565 of the expected molecular mass in large yield from Pichia pastoris. ChiB565 is optimally active at pH 5.0 and 50 °C and stable between pH 4.5 and 9.0 at 50 °C and below. Compared with the commercial chitinase C-6137, which cannot degrade shrimp-shell chitin, ChiB565 hydrolyzes shrimp-shell chitin in addition to colloidal chitin, powdered chitin, and β-1,3-1,4-glucan. The optimal enzyme concentration and reaction time for in vitro degradation of 0.1 g of powdered shrimp shell are 30 U of ChiB565 and 3 h, respectively. A synergistic protein-release effect occurred when ChiB565 and trypsin were incubated in vitro with shrimp shells. Tilapia were fed an experimental diet containing 5% (w/w) shrimp bran and 16.2 U/kg ChiB565, which significantly improved growth and feed conversion compared with a control diet lacking ChiB565. Dietary ChiB565 enhanced nitrogen digestibility and downregulated intestinal IL-1β expression. The immunologically relevant protective effects of dietary ChiB565 were also observed for 2 to 3 days following exposure to pathogenic Aeromonas hydrophila.
authors.affiliation: Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 Zhongguancun South Street, Beijing, 100081, People's Republic of China.
authors.forename: Yuting
authors.initials: Y
authors.lastname: Zhang
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Zhou
authors.forename: Yuchun
authors.initials: Y
authors.lastname: Liu
authors.forename: Yanan
authors.initials: Y
authors.lastname: Cao
authors.forename: Suxu
authors.initials: S
authors.lastname: He
authors.forename: Fengmin
authors.initials: F
authors.lastname: Huo
authors.forename: Chubin
authors.initials: C
authors.lastname: Qin
authors.forename: Bin
authors.initials: B
authors.lastname: Yao
authors.forename: Einar
authors.initials: E
authors.lastname: Ringø
mesh_terms: D000333:Aeromonas / Q000201:enzymology*; D017756:Aquaculture / Q000379:methods*; D002688:Chitinases / Q000378:metabolism*; D014867:Water
chemical_list: D014867:Water; D002688:Chitinases