Metabolic Engineering of Lactobacillus plantarum for Direct l‐Lactic Acid Production From Raw Corn Starch,Biotechnology Journal

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Metabolic Engineering of Lactobacillus plantarum for Direct l‐Lactic Acid Production From Raw Corn Starch
Biotechnology Journal ( IF 3.2 ) Pub Date : 2018-02-22 , DOI: 10.1002/biot.201700517
Kenji Okano ₁ , Gentaro Uematsu ₂ , Shinji Hama ₃ , Tsutomu Tanaka ₄ , Hideo Noda ₃ , Akihiko Kondo ₅ , Kohsuke Honda ₁

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Fermentative production of optically pure lactic acid (LA) has attracted great interest because of the increased demand for plant‐based plastics. For cost‐effective LA production, an engineered Lactobacillus plantarum NCIMB 8826 strain, which enables the production of optically pure l‐LA from raw starch, is constructed. The wild‐type strain produces a racemic mixture of d‐ and l‐LA from pyruvate by the action of the respective lactate dehydrogenases (LDHs). Therefore, the gene encoding D‐LDH (ldhD) is deleted. Although no decrease in d‐LA formation is observed in the ΔldhD mutant, additional disruption of the operon encoding lactate racemase (larA‐E), which catalyzes the interconversion between d‐ and l‐LA, completely abolished d‐LA production. From 100 g L⁻¹ glucose, the ΔldhD ΔlarA‐E mutant produces 87.0 g L⁻¹ of l‐LA with an optical purity of 99.4%. Subsequently, a plasmid is introduced into the ΔldhD ΔlarA‐E mutant for the secretion of α‐amylase from Streptococcus bovis 148. The resulting strain could produce 50.3 g L⁻¹ of l‐LA from raw corn starch with a yield of 0.91 (g per g of consumed sugar) and an optical purity of 98.6%. The engineered L. plantarum strain would be useful in the production of l‐LA from starchy materials.

中文翻译：

代谢工程植物乳杆菌的直接升乳酸从原玉米淀粉

光学纯乳酸（LA）的发酵生产引起了人们的极大兴趣，因为对植物塑料的需求不断增加。为了经济高效地生产LA，我们设计了一种工程化的植物乳杆菌NCIMB 8826菌株，该菌株能够从生淀粉中生产光学纯的l -LA。野生型菌株通过各自的乳酸脱氢酶（LDHs）的作用从丙酮酸中产生d-和l -LA的外消旋混合物。因此，删除了编码D-LDH（ldhD）的基因。尽管在ΔldhD突变体中未观察到d ‐LA形成的减少，但编码乳酸酯消旋酶的操纵子的其他破坏（larA - E）催化d-和l -LA之间的相互转化，完全废除了d -LA的生产。由100克L- ^-1葡萄糖，所述Δ ldhD Δ拉拉-E突变体产生87.0克L- ^-1的升-LA 99.4％的光学纯度。随后，质粒被引入Δ ldhD Δ拉拉-E突变体从α淀粉酶的分泌牛链球菌148得到的菌株可产生50.3克L- ^-1的升从原始玉米淀粉中提取的‐LA，产量为0.91（每克消耗的糖），光学纯度为98.6％。工程化的植物乳杆菌菌株可用于从淀粉质材料生产l -LA。

更新日期：2018-03-21

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