High-yield Production of a Chitinase from Aeromonas veronii B565 as a Potential Feed Supplement for Warm-water aquaculture
会议名称：《中国生物工程学会2014年学术年会暨全国生物技术大会》
会议日期：2014年
学科分类：090502[农学-动物营养与饲料科学] 0905[农学-畜牧学] 09[农学]
关 键 词：Chitinase Aeromonas sp . Overexpression Feed supplements Aquaculture
摘 要：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 Chi B565,, 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, Chi B565 were also observed for 2 to 3 days following exposure, to pathogenic Aeromonas hydrophila.