Liu Jun, Zhang Xinyu, Liu Guodong, Zhao Guoqin, Fang Xiaoran, Song Xin
State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China.
National Glycoengineering Research Center, Shandong University, Qingdao, China.
Front Bioeng Biotechnol. 2022 Mar 9;10:818445. doi: 10.3389/fbioe.2022.818445. eCollection 2022.
Sophorolipids (SLs), an important biosurfactant produced by , were one of the most potential substitutes for chemical surfactants. Few reports on the transcriptional regulation of SLs synthesis and the engineered strains with high-yield SLs were available. In this study, a Rim9-like protein (Rlp) and three transcription factors (, , ) were mined and analyzed, and a progressive enhancement of SLs production was achieved through cumulative knockouts of three genes. The sophorolipid production of reached 97.44 g/L, increased by 50.51% than that of the wild-type strain. Compared with the wild-type strain, the flow of glucose to SLs synthesis pathways was increased, and the synthesis of branched-chain amino acids was reduced in . The amount of UDP-glucose, the substrate for two glycosyltransferases, also increased, and the expression level of the key genes and for SLs synthesis increased by 2.2 times, respectively. The multiple-gene knockout strategy was proved to be highly effective to construct the engineered strain with high-yield SLs production, and this strain was a superior strain for industrial fermentation of SLs and reduced SLs production costs.
槐糖脂（SLs）是由 产生的一种重要生物表面活性剂，是化学表面活性剂最具潜力的替代品之一。关于SLs合成的转录调控以及高产SLs工程菌株的报道很少。在本研究中，挖掘并分析了一种类Rim9蛋白（Rlp）和三种转录因子（ 、 、 ），通过对三个基因的累积敲除实现了SLs产量的逐步提高。 的槐糖脂产量达到97.44 g/L，比野生型菌株提高了50.51%。与野生型菌株相比， 中葡萄糖流向SLs合成途径的流量增加，支链氨基酸的合成减少。两种糖基转移酶的底物UDP-葡萄糖的量也增加，SLs合成关键基因 和 的表达水平分别提高了2.2倍。多基因敲除策略被证明对于构建高产SLs的工程菌株非常有效，该菌株是用于SLs工业发酵的优良菌株，可降低SLs生产成本。
