Laboratory of Microbial Genetics, Department of Genetics, Federal University of Pernambuco, Recife, PE, 50760-901, Brazil.
Laboratory of Plant Genomics and Proteomics, Department of Genetics, Federal University of Pernambuco, Recife, PE, 50760-901, Brazil.
Appl Microbiol Biotechnol. 2021 Feb;105(4):1585-1600. doi: 10.1007/s00253-021-11117-0. Epub 2021 Feb 4.
The yeast Dekkera bruxellensis is well-known for its adaptation to industrial ethanol fermentation processes, which can be further improved if nitrate is present in the substrate. To date, the assimilation of nitrate has been considered inefficient because of the apparent energy cost imposed on cell metabolism. Recent research, however, has shown that nitrate promotes growth rate and ethanol yield when oxygen is absent from the environment. Given this, the present work aimed to identify the biological mechanisms behind this physiological behaviour. Proteomic analyses comparing four contrasting growth conditions gave some clues on how nitrate could be used as primary nitrogen source by D. bruxellensis GDB 248 (URM 8346) cells in anaerobiosis. The superior anaerobic growth in nitrate seems to be a consequence of increased cell metabolism (glycolytic pathway, production of ATP and NADPH and anaplerotic reactions providing metabolic intermediates) regulated by balanced activation of TORC1 and NCR de-repression mechanisms. On the other hand, the poor growth observed in aerobiosis is likely due to an oxidative stress triggered by nitrate when oxygen is present. These results represent a milestone regarding the knowledge about nitrate metabolism and might be explored for future use of D. bruxellensis as an industrial yeast. KEY POINTS: • Nitrate can be regarded as preferential nitrogen source for D. bruxellensis. • Oxidative stress limits the growth of D. bruxellensis in nitrate in aerobiosis. • Nitrate is a nutrient for novel industrial bioprocesses using D. bruxellensis.
酵母德克萨默氏毕赤酵母以适应工业乙醇发酵过程而闻名，如果基质中存在硝酸盐，其适应性可以进一步提高。迄今为止，由于硝酸盐对细胞代谢施加的明显能量成本，人们一直认为硝酸盐的同化效率低下。然而，最近的研究表明，当环境中没有氧气时，硝酸盐可以促进生长速度和乙醇产量。有鉴于此，本工作旨在确定这种生理行为背后的生物学机制。比较四种不同生长条件的蛋白质组学分析为德克萨默氏毕赤酵母 GDB 248（URM 8346）细胞在无氧条件下如何将硝酸盐用作主要氮源提供了一些线索。硝酸盐似乎能够在无氧条件下促进细胞代谢（糖酵解途径、ATP 和 NADPH 的产生以及提供代谢中间产物的回补反应），从而实现卓越的厌氧生长，这种代谢的增强可能是由于 TORC1 和 NCR 去阻遏机制的平衡激活所导致的。另一方面，有氧条件下观察到的生长不良可能是由于存在氧气时硝酸盐引发的氧化应激所致。这些结果代表了关于硝酸盐代谢知识的一个里程碑，并且可能会被探索用于未来将德克萨默氏毕赤酵母作为工业酵母的用途。关键点：• 硝酸盐可以被视为德克萨默氏毕赤酵母的优先氮源。• 有氧条件下，硝酸盐限制了德克萨默氏毕赤酵母的生长。• 硝酸盐是使用德克萨默氏毕赤酵母进行新型工业生物过程的一种营养物质。
