Zheng Zhaojuan, Lin Xi, Jiang Ting, Ye Weihua, Ouyang Jia
College of Chemical Engineering, Nanjing Forestry University, Nanjing, 210037, People's Republic of China.
Jiangsu Key Lab of Biomass-Based Green Fuels and Chemicals, Nanjing, 210037, People's Republic of China.
Biotechnol Lett. 2016 Aug;38(8):1331-9. doi: 10.1007/s10529-016-2109-0. Epub 2016 May 20.
To investigate the xylose operon and properties of xylose isomerase and xylulokinase in Bacillus coagulans that can effectively ferment xylose to lactic acid.
The xylose operon is widely present in B. coagulans. It is composed of four putative ORFs. Novel xylA and xylB from B. coagulans NL01 were cloned and expressed in Escherichia coli. Sequence of xylose isomerase was more conserved than that of xylulokinase. Both the enzymes exhibited maximum activities at pH 7-8 but with a high temperature maximum of 80-85 °C, divalent metal ion was prerequisite for their activation. Xylose isomerase and xylulokinase were most effectively activated by Ni(2+) and Co(2+), respectively.
Genomic analysis of xylose operon has contributed to understanding xylose metabolism in B. coagulans and the novel xylose isomerase and xylulokinase might provide new alternatives for metabolic engineering of other strains to improve their fermentation performance on xylose.
研究凝结芽孢杆菌中可有效将木糖发酵为乳酸的木糖操纵子以及木糖异构酶和木酮糖激酶的特性。
木糖操纵子广泛存在于凝结芽孢杆菌中。它由四个假定的开放阅读框组成。从凝结芽孢杆菌NL01中克隆了新的木糖异构酶基因（xylA）和木酮糖激酶基因（xylB），并在大肠杆菌中进行了表达。木糖异构酶的序列比木酮糖激酶的序列更保守。这两种酶在pH 7 - 8时均表现出最大活性，但最适温度为80 - 85℃，二价金属离子是其激活的先决条件。木糖异构酶和木酮糖激酶分别最有效地被Ni(2+)和Co(2+)激活。
木糖操纵子的基因组分析有助于了解凝结芽孢杆菌中的木糖代谢，新型木糖异构酶和木酮糖激酶可能为其他菌株的代谢工程提供新的选择，以提高它们对木糖的发酵性能。
