Qiu Yejuan, Qiu Zhongyang, Xia Jun, Liu Xiaoyan, Zhang Hanwen, Yang Yuxiang, Hou Wenyi, Li Xiangqian, He Jianlong
Jiangsu Provincial Key Construction Laboratory of Probiotics Preparation, Huaiyin Institute of Technology, 1 Meicheng Road, Huaian, 223003, Jiangsu Province, China.
Jiangsu Key Laboratory for Biomass-Based Energy and Enzyme Technology, Huaiyin Normal University, 111 Changjiang West Road, Huaian, 223300, Jiangsu Province, China.
Appl Biochem Biotechnol. 2023 Feb;195(2):816-831. doi: 10.1007/s12010-022-04168-0. Epub 2022 Oct 7.
The raw material cost of lactic acid fermentation accounts for the main part of the production cost, and this necessitates the exploration of the efficient use of cheap raw materials in lactic acid production. We compared the outcomes of the homologous expressions of xylose transporters (xylFGH, xylE, araE, and xylT), 6-phosphofructokinase (pfkA), fructose-bisphosphate aldolase (fbaA), and their co-expression in Lactococcus lactis IO-1 on lactic acid production using xylose as the raw material. We found that the production rate of lactic acid on xylose fermentation by L. lactis IO-1 overexpressing fbaA was the highest (14.42%). Among the xylose transporters investigated, XylT had the strongest xylose transport capacity in L. lactis IO-1, with an increase in the lactic acid production rate by 10.38%. The genes near the overexpression of fbaA or xylT in the metabolic pathway were more upregulated than the distant genes. The co-expression of fbaA and xylT increased the production rate of lactic acid by 27.84% on xylose fermentation by L. lactis IO-1. This work presents a novel strategy for the simultaneous enhancement of the expression of important genes at the beginning and midway of the xylose metabolic pathway of L. lactis IO-1, which could greatly improve the target production.
乳酸发酵的原材料成本占生产成本的主要部分，因此有必要探索在乳酸生产中有效利用廉价原材料的方法。我们比较了木糖转运蛋白（xylFGH、xylE、araE和xylT）、6-磷酸果糖激酶（pfkA）、果糖-1,6-二磷酸醛缩酶（fbaA）在乳酸乳球菌IO-1中的同源表达及其共表达对以木糖为原料生产乳酸的影响。我们发现，过表达fbaA的乳酸乳球菌IO-1在木糖发酵上的乳酸生产率最高（14.42%）。在所研究的木糖转运蛋白中，XylT在乳酸乳球菌IO-1中的木糖转运能力最强，乳酸生产率提高了10.38%。代谢途径中fbaA或xylT过表达附近的基因比远处的基因上调程度更高。fbaA和xylT的共表达使乳酸乳球菌IO-1在木糖发酵上的乳酸生产率提高了27.84%。这项工作提出了一种新策略，可同时增强乳酸乳球菌IO-1木糖代谢途径起始和中间重要基因的表达，从而大大提高目标产量。
