William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, 140 W 19th Avenue, Columbus, OH 43210, USA.
William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, 140 W 19th Avenue, Columbus, OH 43210, USA; School of Pharmaceutical Engineering and Life Sciences, Changzhou University, 1 Ge Hu Road, Jiangsu 213164, China.
Metab Eng. 2015 Jan;27:46-56. doi: 10.1016/j.ymben.2014.10.005. Epub 2014 Oct 29.
Propionibacterium freudenreichii subsp. shermanii naturally forms propionic acid as the main fermentation product with acetate and succinate as two major by-products. In this study, overexpressing the native propionyl-CoA:succinate CoA transferase (CoAT) in P. shermanii was investigated to evaluate its effects on propionic acid fermentation with glucose, glycerol, and their mixtures as carbon source. In general, the mutant produced more propionic acid, with up to 10% increase in yield (0.62 vs. 0.56g/g) and 46% increase in productivity (0.41 vs. 0.28g/Lh), depending on the fermentation conditions. The mutant also produced less acetate and succinate, with the ratios of propionate to acetate (P/A) and succinate (P/S) in the final product increased 50% and 23%, respectively, in the co-fermentation of glucose/glycerol. Metabolic flux analysis elucidated that CoAT overexpression diverted more carbon fluxes toward propionic acid, resulting in higher propionic acid purity and a preference for glycerol over glucose as carbon source.
谢氏丙酸杆菌亚种自然形成丙酸作为主要发酵产物，同时生成乙酸盐和琥珀酸盐作为两种主要副产物。在本研究中，过表达谢氏丙酸杆菌中的天然丙酰辅酶 A:琥珀酸辅酶 A 转移酶（CoAT），以评估其对丙酸发酵的影响，发酵碳源为葡萄糖、甘油及其混合物。一般来说，与野生型相比，突变体产生更多的丙酸，产率提高了 10%（0.62 对 0.56g/g），生产力提高了 46%（0.41 对 0.28g/Lh），这取决于发酵条件。突变体还产生较少的乙酸盐和琥珀酸盐，最终产物中丙酸与乙酸盐（P/A）和琥珀酸盐（P/S）的比例分别提高了 50%和 23%，在葡萄糖/甘油共发酵中。代谢通量分析表明，CoAT 的过表达将更多的碳通量转移到丙酸中，从而提高了丙酸的纯度，并优先选择甘油作为碳源而不是葡萄糖。
