Laothanachareon Thanaporn, Bruinsma Lyon, Nijsse Bart, Schonewille Tom, Suarez-Diez Maria, Tamayo-Ramos Juan Antonio, Martins Dos Santos Vitor A P, Schaap Peter J
Laboratory of Systems and Synthetic Biology, Department of Agrotechnology and Food Sciences, Wageningen University & Research, 6708 WE Wageningen, The Netherlands.
Enzyme Technology Laboratory, Biorefinery and Bioproduct Research Group, National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Khlong Luang, Pathumthani 12120, Thailand.
J Fungi (Basel). 2021 May 23;7(6):409. doi: 10.3390/jof7060409.
is the major industrial citrate producer worldwide. Export as well as uptake of citric acid are believed to occur by active, proton-dependent, symport systems. Both are major bottlenecks for industrial citrate production. Therefore, we assessed the consequences of deleting the gene encoding the citrate exporter, effectively blocking active citrate export. We followed the consumption of glucose and citrate as carbon sources, monitored the secretion of organic acids and carried out a thorough transcriptome pathway enrichment analysis. Under controlled cultivation conditions that normally promote citrate secretion, the knock-out strain secreted negligible amounts of citrate. Blocking active citrate export in this way led to a reduced glucose uptake and a reduced expression of high-affinity glucose transporter genes, and . The glyoxylate shunt was strongly activated and an increased expression of the OAH gene was observed, resulting in a more than two-fold higher concentration of oxalate in the medium. Deletion of did not affect citrate uptake suggesting that citrate export and citrate uptake are uncoupled from the system.
是全球主要的工业柠檬酸生产商。柠檬酸的输出和摄取被认为是通过主动的、质子依赖的同向转运系统进行的。这两者都是工业柠檬酸生产的主要瓶颈。因此，我们评估了删除编码柠檬酸输出蛋白的基因的后果，有效地阻断了柠檬酸的主动输出。我们跟踪了葡萄糖和柠檬酸作为碳源的消耗情况，监测了有机酸的分泌，并进行了全面的转录组途径富集分析。在通常促进柠檬酸分泌的受控培养条件下，敲除菌株分泌的柠檬酸量可忽略不计。以这种方式阻断柠檬酸的主动输出导致葡萄糖摄取减少，高亲和力葡萄糖转运蛋白基因和的表达降低。乙醛酸循环被强烈激活，观察到OAH基因的表达增加，导致培养基中草酸盐浓度提高了两倍多。的缺失不影响柠檬酸的摄取，这表明柠檬酸的输出和摄取与该系统解偶联。
