2026-07-19T23:00:37Zhttps://riubu.ubu.es/oai/request

oai:riubu.ubu.es:10259/57782024-07-25T07:26:03Zcom_10259_9476com_10259.4_106com_10259_2604col_10259_9477

00925njm 22002777a 4500 dc Laothanachareon, Thanaporm author Bruinsma, Lyon author Nijsse, Bart author Schonewille, Tom author Suarez Diez, Maria author Tamayo Ramos, Juan Antonio author Santos, Vitor AP Martins dos author Schaap, Peter J. author 2021-06 Aspergillus niger 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 citT gene encoding the A. niger 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, mstG and mstH. 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 citT did not affect citrate uptake suggesting that citrate export and citrate uptake are uncoupled from the system. http://hdl.handle.net/10259/5778 10.3390/jof7060409 2309-608X Aspergillus niger citrate exporter citT gene cexA gene transcriptome citric acid oxalic acid Global transcriptional response of aspergillus niger to blocked active citrate export through deletion of the exporter gene