Department of Biochemical Engineering, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, Debrecen, H-4032, Hungary.
Institute of Chemical, Environmental & Bioscience Engineering, TU Wien, Getreidemarkt 9, 1060, Vienna, Austria.
Appl Microbiol Biotechnol. 2019 Apr;103(7):2889-2902. doi: 10.1007/s00253-018-09607-9. Epub 2019 Feb 13.
Citric acid production by Aspergillus niger and itaconic acid production by Aspergillus terreus are two major examples of technical scale fungal fermentations based on metabolic overflow of primary metabolism. Both organic acids are formed by the same metabolic pathway, but whereas citric acid is the end product in A. niger, A. terreus performs two additional enzymatic steps leading to itaconic acid. Despite of this high similarity, the optimization of the production process and the mechanism and regulation of overflow of these two acids has mostly been investigated independently, thereby ignoring respective knowledge from the other. In this review, we will highlight where the similarities and the real differences of these two processes occur, which involves various aspects of medium composition, metabolic regulation and compartmentation, transcriptional regulation, and gene evolution. These comparative data may facilitate further investigations of citric acid and itaconic acid accumulation and may contribute to improvements in their industrial production.
黑曲霉柠檬酸生产和土曲霉富马酸生产是基于初级代谢物代谢溢出的两种主要真菌发酵技术规模的例子。这两种有机酸都是通过相同的代谢途径形成的，但柠檬酸是黑曲霉的终产物，而土曲霉则进行另外两个酶促步骤，导致富马酸的形成。尽管有如此高的相似性，但这两种酸的生产过程的优化以及溢出的机制和调节主要是独立进行的，从而忽略了彼此的知识。在这篇综述中，我们将强调这两个过程的相似之处和真正的差异发生在哪里，这涉及到培养基组成、代谢调节和区室化、转录调节以及基因进化等各个方面。这些比较数据可能有助于进一步研究柠檬酸和富马酸的积累，并有助于提高它们的工业生产。
