Department of Chemistry, Dalhousie University, 6274 Coburg Road, PO Box 15000, Halifax, NS, B3H 4R2, Canada.
Appl Biochem Biotechnol. 2019 Jan;187(1):163-175. doi: 10.1007/s12010-018-2817-0. Epub 2018 Jun 18.
Accumulation of succinate as a fermentation product of Fusobacterium varium was enhanced when the anaerobic bacterium was grown on complex peptone medium supplemented with fumarate. Residual substrates and fermentation products were determined by proton NMR spectroscopy. Cells collected from the fumarate-supplemented medium (8-10 h after inoculation) supported the conversion of fumarate to succinate when suspended with fumarate and a co-substrate (glucose, sorbitol, or glycerol). Succinate production was limited by the availability of fumarate or reducing equivalents supplied by catabolism of a co-substrate via the Embden-Meyerhof-Parnas (EMP) pathway. The choice of reducing co-substrate influenced the yield of acetate and lactate as side products. High conversions of fumarate to succinate were achieved over pH 6.6-8.2 and initial fumarate concentrations up to 300 mM. However, at high substrate concentrations, intracellular retention of succinate reduced extracellular yields. Overall, the efficient utilization of fumarate (≤ 400 mM) combined with the significant extracellular accumulation of succinate (corresponding to ≥ 70% conversion) indicated the effective utilization of fumarate as a terminal electron acceptor by F. varium and the potential of the methodology for the bioproduction of succinate.
当厌氧细菌在添加富马酸盐的复杂蛋白胨培养基上生长时，产变体梭菌（Fusobacterium varium）的琥珀酸积累作为发酵产物而增加。通过质子 NMR 光谱法测定残留的底物和发酵产物。当用富马酸盐和共底物（葡萄糖、山梨糖醇或甘油）悬浮收集来自添加富马酸盐的培养基中的细胞（接种后 8-10 小时）时，支持富马酸盐转化为琥珀酸。琥珀酸的产生受通过 EMP 途径代谢共底物提供的富马酸盐或还原当量的可用性限制。还原共底物的选择会影响作为副产物的乙酸盐和乳酸盐的产率。在 pH 6.6-8.2 和初始富马酸盐浓度高达 300mM 的条件下，可以实现富马酸盐到琥珀酸的高转化率。然而，在高底物浓度下，细胞内琥珀酸的保留会降低细胞外的产率。总的来说，富马酸盐的有效利用（≤400mM）以及琥珀酸的显著细胞外积累（对应于≥70%的转化率）表明了产变体梭菌有效利用富马酸盐作为末端电子受体的能力，以及该方法在琥珀酸生物生产中的潜力。
