产环糊精葡萄糖基转移酶菌株的筛选、鉴定与应用研究

Screening,identification and applications of a cyclodextrin glucanotransferase-producing microbial strain

利用产环糊精葡萄糖基转移酶(CGTase)菌株快速筛选法结合芦丁转糖基酶反应,筛选获得一株所产CGTase可高效转化芦丁的菌株。16SrRNA鉴定表明,此菌株和地衣芽孢杆菌(Bacillus licheniformis)有100%的同源性。结合形态和生理生化鉴定,确定此菌株为地衣芽孢杆菌,命名为Bacillus licheniformis SK13.002。该菌株在pH约为10时生长良好,且具有最高的产酶量,显示其嗜碱性。此菌株所产酶以淀粉作底物所产环糊精为β-环糊精和γ-环糊精,其中β-环糊精所占比例为83.3%;两者产量分别达到20.9g/L和4.2g/L。直接利用浓缩酶液进行芦丁的糖基化,则可以得到近70%的转化率。

Using rapid screening method combined with enzymatic transglycosylation reaction of rutin,a microbial strain producing cyclodextrin glucanotransferase （CGTase）with highly efficient transglycosylation of rutin was isolated from soil. Through morphological, biochemical, physiological and 16S rRNA analyses, this strain was identified as Bacillus licheniformis SK13.002 with a 100% identity.This strain grew well and produced the largest amount of CGTase at a pH around 10 indicating that it was alkaliphilic.The CGTase from this strain was utilized to convert 5% of soluble starch and the results revealed that the enzyme produced mainly β-CD at 83.3% of the total CDs yield and no α-CD was formed after 24h of reaction.The produced β-and -γ-CDs corresponded to 20.9g/L and 4.2g/L, respectively. The enzyme was also used to carry out transglycosylation reaction of rutin; under the optimized enzymatic reaction conditions,conversion rate of rutin reached near 70%.