State Key Laboratory of Food Nutrition and Safety, Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, College of Biotechnology, Tianjin University of Science & Technology, Tianjin, 300457, People's Republic of China.
State Key Laboratory of Food Nutrition and Safety, Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, College of Biotechnology, Tianjin University of Science & Technology, Tianjin, 300457, People's Republic of China.
Food Microbiol. 2021 May;95:103684. doi: 10.1016/j.fm.2020.103684. Epub 2020 Nov 26.
Shanxi aged vinegar (SAV), a Chinese traditional vinegar, is produced by various microorganisms. Ammonium is an important nitrogen source for microorganisms and a key intermediate for the utilization of non-ammonium nitrogen sources. In this work, an ammonium metabolic network during SAV fermentation was constructed through the meta-transcriptomic analysis of in situ samples, and the potential mechanism of acid affecting ammonium metabolism was revealed. The results showed that ammonium was enriched as the acidity increased. Meta-transcriptomic analysis showed that the conversion of glutamine to ammonia is the key pathway of ammonium metabolism in vinegar and that Lactobacillus and Acetobacter are the dominant genera. The construction and analysis of the metabolic network showed that amino acid metabolism, nucleic acid metabolism, pentose phosphate pathway and energy metabolism were enhanced to resist acid damage to the intracellular environment and cell structures. The enhancement of nitrogen assimilation provides nitrogen for metabolic pathways that resist acid cytotoxicity. In addition, the concentration gradient allows ammonium to diffuse outside the cell, which causes ammonium to accumulate during fermentation.
山西老陈醋（SAV）是一种中国传统醋，由多种微生物共同酿造。铵是微生物的重要氮源，也是利用非铵氮源的关键中间产物。在本研究中，通过原位样品的代谢组学分析，构建了 SAV 发酵过程中的铵代谢网络，并揭示了酸影响铵代谢的潜在机制。结果表明，随着酸度的增加，铵被富集。代谢组学分析表明，谷氨酰胺向氨的转化是醋中铵代谢的关键途径，而乳杆菌属和醋杆菌属是主要的属。代谢网络的构建和分析表明，氨基酸代谢、核酸代谢、戊糖磷酸途径和能量代谢增强，以抵抗细胞内环境和细胞结构的酸损伤。氮同化的增强为抵抗酸细胞毒性的代谢途径提供了氮。此外，浓度梯度使铵能够扩散到细胞外，导致发酵过程中铵的积累。
