title: Enhanced extracellular production of recombinant Bacillus deramificans pullulanase in Escherichia coli through induction mode optimization and a glycine feeding strategy.
abstract: Process optimization strategies were developed to improve extracellular production of recombinant Bacillus deramificans pullulanase in Escherichia coli. Cell growth and pullulanase production in shake-flask cultures were investigated as a function of the concentration of added glycine, and the type and concentration of inducer. From the results of these experiments, a fed-batch fermentation strategy for high-cell-density cultivation was applied in a 3-L fermentor. The gradual addition of lactose was utilized for the induction of protein expression. The optimal lactose feeding rate and induction point were 0.4gL(-1)h(-1) and a dry cell weight (DCW) of 15gL(-1), respectively. Furthermore, a glycine feeding strategy was formulated to promote the secretion of recombinant protein. The optimal total and extracellular pullulanase activity were 2523.5 and 1567.9UmL(-1), respectively, which represent 1.2 and 22.6-fold increases compared with those observed under unoptimized conditions.
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China; School of Biotechnology and Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China.
authors.forename: Chun
authors.initials: C
authors.lastname: Zou
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China; School of Biotechnology and Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China.
authors.forename: Xuguo
authors.initials: X
authors.lastname: Duan
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China; School of Biotechnology and Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China. Electronic address: jingwu@jiangnan.edu.cn.
authors.forename: Jing
authors.initials: J
authors.lastname: Wu
mesh_terms: D001407:Bacillus / Q000201:enzymology*; D049109:Cell Proliferation; D004926:Escherichia coli / Q000378:metabolism*; D005998:Glycine / Q000008:administration & dosage; D006026:Glycoside Hydrolases / Q000096:biosynthesis* / Q000378:metabolism; D007544:Isopropyl Thiogalactoside / Q000008:administration & dosage; D007785:Lactose / Q000008:administration & dosage
chemical_list: D007544:Isopropyl Thiogalactoside; D006026:Glycoside Hydrolases; C100181:pullulanase; D007785:Lactose; D005998:Glycine
keywords: Escherichia coli; Extracellular secretion; Glycine; Glycine feeding strategy; Pullulanase