Metabolic Engineering Research Unit, School of Biotechnology, Suranaree University of Technology, 111 University Avenue, Suranaree, Muang, Nakhon Ratchasima 30000, Thailand.
Metabolic Engineering Research Unit, School of Biotechnology, Suranaree University of Technology, 111 University Avenue, Suranaree, Muang, Nakhon Ratchasima 30000, Thailand.
Bioresour Technol. 2024 Sep;407:131137. doi: 10.1016/j.biortech.2024.131137. Epub 2024 Jul 21.
Klebsiella oxytoca KP001-TF60 (ΔadhEΔpta-ackAΔldhAΔbudABΔpflBΔtdcDΔpmd) was re-engineered to direct more carbon flux towards succinate production with less acetate. Glucose uptake, cell growth, and carbon distribution were restricted by alterations in relative expressions and nucleotide sequences of genes associated with PEP and pyruvate metabolisms. Transcripts of pck, ppc, and frd genes were up-regulated for enhancing NADH reoxidation during succinate production while increased pyk and tdcE transcripts were observed due to maintenance of acetyl-CoA through the oxidative branch of TCA cycle. Based on whole-genome sequencing, several genes in sugars-specific PTS (ptsG, bglF, chbR, fruA, mtlR, and treY), ABC transporters (alsK, and rbsK), Major Facilitator Superfamily (uhpB and setB), and catabolite repression (cyaA and csrB) were found to be mutated. The strain produced succinate yield up to 0.89 g/g (∼80 % theoretical maximum) with acetate < 1 g/L, and may be one of the succinate producers applied in an industrial-production scale with simplified purification processes.
将 KP001-TF60（ΔadhEΔpta-ackAΔldhAΔbudABΔpflBΔtdcDΔpmd）重编程为粪产碱杆菌，使其在生产琥珀酸时将更多的碳通量引导至琥珀酸生产，同时减少乙酸的产生。通过改变与 PEP 和丙酮酸代谢相关的基因的相对表达和核苷酸序列，限制了葡萄糖摄取、细胞生长和碳分布。为了在生产琥珀酸时增强 NADH 的再氧化，上调了 pck、ppc 和 frd 基因的转录本，而由于通过 TCA 循环的氧化分支维持乙酰辅酶 A，观察到了更多的 pyk 和 tdcE 转录本。基于全基因组测序，发现 PTS（ptsG、bglF、chbR、fruA、mtlR 和 treY）、ABC 转运蛋白（alsK 和 rbsK）、主要易化因子超家族（uhpB 和 setB）和分解代谢物阻遏（cyaA 和 csrB）中的几个基因发生了突变。该菌株的琥珀酸产量高达 0.89 g/g（约 80%理论最大值），乙酸<1 g/L，可能是在工业生产规模中应用的琥珀酸生产菌之一，具有简化的纯化工艺。
