摘要
β-半乳糖苷酶是一类非常重要的糖苷水解酶,已被广泛应用于食品工业降低乳制品中的乳糖含量.某些种类的β-半乳糖苷酶还具有转糖基活性,近年来被应用于合成低聚半乳糖和半乳糖苷化合物.通过单因子试验和正交试验,对肠杆菌Enterobacter cloacae B5产生转糖基β-半乳糖苷酶的培养基组成及发酵条件进行了优化.结果表明,以无机盐溶液I(CaCl20.011%、MnSO40.0001%、MgSO4.7H2O0.03%、KH2PO40.005%、FeSO4.7H2O0.003%)、乳糖1.5%、酵母粉2%、蛋白胨0.5%、起始pH8.5的培养基在25℃培养E.cloacaeB5菌株38h,产酶量达到最高值4.663UmL-1,大约是未优化时的3倍.通过优化产酶条件提高了全细胞酶源的酶活量,不仅为功能性低聚半乳糖的生产降低了成本,同时也为商业化β-半乳糖苷酶的大量提纯降低了成本.
β-galactosidases are among the most important glycosyl hydrolases. They have been applied in the food industry for decades for reducing the lactose content in milk. Some galactosidases also display transglycosylation activity, and have been used to synthesize galacto-oligosaccharides and galactose containing chemicals in recent years. Enterobacter cloacae B5 produced a transglycosylatingβ-galactosidase. The medium and fermentation conditions for itsβ-galactosidase production were optimized by single factor and orthogonal experiments. β-galactosidase activity in E. cloacae B5 was increased by three folds （4. 663 U mL^-1） in the medium （pH 8.5） containing inorganic salt Ⅰ （CaCl2 0. 011, MnSO4 0.0001% , MgSO4·7H2O 0. 03% , KH2PO4 0. 005% , FeSO4·7H2O 0. 003% ） , 1.5% lactose, 2% yeast extract and 0. 5% peptone when cultured at 25 22 for 38 h. Enzyme amounts were increased in whole cells, which reduced not only the cost for production of prebiotic galacto-oligosaccharides, but also the cost for purification of commercialβ-galactosidases. Fig 2, Tab 4, Ref 12
出处
《应用与环境生物学报》
CAS
CSCD
北大核心
2008年第1期118-121,共4页
Chinese Journal of Applied and Environmental Biology
基金
国家"十五"科技攻关计划项目(2004BA713B04-06)
国家"863计划"项目(2006AA10Z338)~~
