Fukui Keita, Nanatani Kei, Nakayama Mayumi, Hara Yoshihiko, Tokura Mitsunori, Abe Keietsu
Frontier Research Laboratories, Institute for Innovation, Ajinomoto Co., Inc., 1-1 Suzuki-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa 210-8681, Japan.
Department of Microbial Resources, Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, Sendai, Miyagi 981-8555, Japan.
J Biosci Bioeng. 2019 Apr;127(4):465-471. doi: 10.1016/j.jbiosc.2018.10.004. Epub 2018 Nov 2.
After deleting the gene encoding succinate dehydrogenase, Corynebacterium glutamicum can produce succinate and a considerable amount of acetate and pyruvate as by-products from glucose metabolism, under aerobic conditions. Recently, we identified ynfM in Pantoea ananatis (PaynfM) as a gene encoding a dicarboxylate transporter and found a homologous gene (CgynfM) in C. glutamicum. In this study, we examined dicarboxylate production using C. glutamicum strains expressing CgynfM. When C. glutamicum expressing the CgynfM gene was cultured under aerobic conditions, the sugar-consumption rate increased significantly, succinate accumulation increased from 66 mM to 110 mM, and pyruvate and acetate co-production decreased significantly. Pyruvate decreased from 120 mM to 6.2 mM, and acetate decreased to undetectable level. CgYnfM restored succinate production under anaerobic conditions in C. glutamicum strain AJ110655ΔsucE1, in which the gene encoding the major succinate exporter (sucE1) was deleted. CgynfM expression also increased α-ketoglutarate production from 5.1 mM to 24 mM under anaerobic conditions. Collectively, these results suggest that YnfM from C. glutamicum functions as a dicarboxylate transporter that is applicable to the succinate production.
在删除编码琥珀酸脱氢酶的基因后，谷氨酸棒杆菌在有氧条件下可从葡萄糖代谢中产生琥珀酸以及相当数量的副产物乙酸和丙酮酸。最近，我们在菠萝泛菌（Pantoea ananatis）中鉴定出ynfM（PaynfM）作为编码二羧酸转运蛋白的基因，并在谷氨酸棒杆菌中发现了一个同源基因（CgynfM）。在本研究中，我们使用表达CgynfM的谷氨酸棒杆菌菌株检测了二羧酸的产生。当在有氧条件下培养表达CgynfM基因的谷氨酸棒杆菌时，糖消耗率显著增加，琥珀酸积累量从66 mM增加到110 mM，丙酮酸和乙酸的联产显著减少。丙酮酸从120 mM降至6.2 mM，乙酸降至检测不到的水平。CgYnfM在谷氨酸棒杆菌菌株AJ110655ΔsucE1的厌氧条件下恢复了琥珀酸的产生，在该菌株中编码主要琥珀酸外排蛋白（sucE1）的基因被删除。在厌氧条件下，CgynfM的表达也使α-酮戊二酸的产量从5.1 mM增加到24 mM。总体而言，这些结果表明来自谷氨酸棒杆菌的YnfM作为一种二羧酸转运蛋白，适用于琥珀酸的生产。
