title: Medium optimization for the production of thermal stable beta-glucanase by Bacillus subtilis ZJF-1A5 using response surface methodology.
abstract: Polysaccharides, such as barley flour, dextrin and soluble starch, were better carbon sources than monosaccharides and disaccharides, such as glucose and maltose, for cell growth of Bacillus subtilis ZJF-1A5 and beta-glucanase production. beta-Glucanase produced by B. subtilis ZJF-1A5 was associated partially with cell growth and increased significantly when cells entered stationary phase; yeast extract was the best nitrogen source, followed by soybean flour. All inorganic nitrogen sources chosen in the experiments were not favorable for cell growth and enzyme production. A fractional factorial design (2(6-2)) was applied to elucidate medium components that significantly affect beta-glucanase production. The concentration of barley flour, corn flour and soybean flour in medium were significant factors. The steepest ascent method was used to locate the optimal domain and a central composite design was used to estimate the quadratic response surface from which the factor levels for maximum production of beta-glucanase were determined. The composition of fermentation medium optimized with response surface methodology was (g/l): barley flour, 63.5; corn flour, 44.8; KH2PO4, 1.0; MgSO4 x 7H2O, 0.1; CaCl2, 0.1. beta-Glucanase activity was 251 U/ml at 48 h using optimized medium, 1.4 times higher than that in original medium.
authors.affiliation: College of Biosystem Engineering and Food Science, Zhejiang University, Hangzhou, China.
authors.forename: Xing-Jun
authors.initials: XJ
authors.lastname: Tang
authors.forename: Guo-Qing
authors.initials: GQ
authors.lastname: He
authors.forename: Qi-He
authors.initials: QH
authors.lastname: Chen
authors.forename: Xiu-Yan
authors.initials: XY
authors.lastname: Zhang
authors.forename: Mokhtar A M
authors.initials: MA
authors.lastname: Ali
mesh_terms: D000704:Analysis of Variance; D001412:Bacillus subtilis / Q000254:growth & development* / Q000378:metabolism*; D019149:Bioreactors; D050260:Carbohydrate Metabolism; D005285:Fermentation; D006026:Glycoside Hydrolases / Q000096:biosynthesis*; D001467:Hordeum; D016014:Linear Models; D012044:Regression Analysis; D013025:Glycine max; D003313:Zea mays
chemical_list: D006026:Glycoside Hydrolases; C028020:licheninase