Institute of Fermentation Engineering, College of Biological and Environmental Engineering, Zhejiang University of Technology, 18# Chaowang Road, Hangzhou 310014, PR China.
Bioresour Technol. 2013 Mar;131:13-20. doi: 10.1016/j.biortech.2012.12.021. Epub 2012 Dec 14.
Validamycin A is widely used to control Basidiomycetes, which causes sheath blight disease in rice, potatoes, vegetables, and other crops as well as dumping-off disease in vegetable seedlings, cotton, sugar beets, and other plants. In order to improve the content of validamycin A in the commercial products, valG from Streptomyces hygroscopicus was successfully cloned into Escherichia coli BL21(DE3) and was directly employed as the biocatalyst in the biotransformation from validoxylamine A to validamycin A with the existence of d-cellobiose using the free resting cells in the present study. The fermentation medium was optimized through single factor experiment and response surface method. With the optimized medium, which contained lactose 4.7g/L, yeast extract 49.5g/L, ammonium chloride 2.7g/L, potassium phosphate buffer solution 110mL/L, Ca(2+) 0.0352g/L, the biomass yield and enzyme activity reached 5.5g/L and 1.49U/mL, respectively, which were nearly twice higher than those with initial medium.
井冈霉素 A 被广泛用于防治引起水稻、土豆、蔬菜等作物纹枯病和蔬菜、棉花、甜菜等作物烂种的担子菌。为了提高井冈霉素 A 在商业产品中的含量,本研究采用来源于吸水链霉菌(Streptomyces hygroscopicus)的 valG 基因,将其成功克隆到大肠杆菌 BL21(DE3)中,并在含有纤维二糖的条件下,利用游离的静止细胞直接作为生物催化剂,将 validoxylamine A 生物转化为井冈霉素 A。通过单因素实验和响应面法对发酵培养基进行了优化。在优化后的培养基中(含有 4.7g/L 乳糖、49.5g/L 酵母提取物、2.7g/L 氯化铵、110mL/L 磷酸钾缓冲液、0.0352g/L Ca(2+)),生物量和酶活分别达到 5.5g/L 和 1.49U/mL,分别是初始培养基的近两倍。