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Malic Enzyme Facilitates d-Lactate Production through Increased Pyruvate Supply during Anoxic Dark Fermentation in Synechocystis sp. PCC 6803.
ACS Synthetic Biology ( IF 4.7 ) Pub Date : 2020-01-31 , DOI: 10.1021/acssynbio.9b00281
Ryota Hidese 1 , Mami Matsuda 1, 2 , Takashi Osanai 3 , Tomohisa Hasunuma 1, 2 , Akihiko Kondo 1, 2, 4
Affiliation  

d-Lactate is one of the most valuable compounds for manufacturing biobased polymers. Here, we have investigated the significance of endogenous malate dehydrogenase (decarboxylating) (malic enzyme, ME), which catalyzes the oxidative decarboxylation of malate to pyruvate, in d-lactate biosynthesis in the cyanobacterium Synechocystis sp. PCC6803. d-Lactate levels were increased by 2-fold in ME-overexpressing strains, while levels in ME-deficient strains were almost equivalent to those in the host strain. Dynamic metabolomics revealed that overexpression of ME led to increased turnover rates in malate and pyruvate metabolism; in contrast, deletion of ME resulted in increased pool sizes of glycolytic intermediates, probably due to sequential feedback inhibition, initially triggered by malate accumulation. Finally, both the loss of the acetate kinase gene and overexpression of endogenous d-lactate dehydrogenase, concurrent with ME overexpression, resulted in the highest production of d-lactate (26.6 g/L) with an initial cell concentration of 75 g-DCW/L after 72 h fermentation.

中文翻译:

苹果酸酶通过集胞藻sp的缺氧黑暗发酵过程中丙酮酸供应的增加促进d-乳酸的生产。PCC 6803。

d-乳酸是生产生物基聚合物最有价值的化合物之一。在这里,我们研究了内源性苹果酸脱氢酶(脱羧)(苹果酸酶,ME)的重要性,该酶催化苹果酸在蓝藻Synechocystis sp中的乳酸合成中氧化脱羧为丙酮酸。PCC6803。在过表达ME的菌株中,d-乳酸水平增加了2倍,而在缺乏ME的菌株中,d-乳酸水平几乎与宿主菌株中的水平相同。动态代谢组学研究表明,ME的过表达导致苹果酸和丙酮酸代谢的周转率增加。相反,ME的删除可能导致糖酵解中间体库的增加,这可能是由于顺序反馈抑制(最初由苹果酸积累触发)所致。最后,
更新日期:2020-02-13
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