强化乙醛酸和TCA循环对克雷伯氏菌合成1,3-丙二醇的影响  

Strengthening glyoxylate bypass and the TCA cycle improved 1,3-propanediol production in Klebsiella pneumoniae

作　　者：谢梦梦 胡会涛 陆信曜 宗红 诸葛斌[1,2,3] XIE Mengmeng;HU Huitao;LU Xinyao;ZONG Hong;ZHUGE Bin(Key Laboratory of Carbohydrate Chemistry and Biotechnology,Ministry of Education,Jiangnan University,Wuxi 214122,China;The Key Laboratory of Industrial Biotechnology,Ministry of Education,Jiangnan University,School of Biotechnology,Wuxi 214122,China;Research Centre of Industrial Microbiology,Jiangnan University,Wuxi 214122,China)

机构地区：[1]糖化学与生物技术教育部重点实验室(江南大学),江苏无锡214122 [2]工业生物技术教育部重点实验室(江南大学),江苏无锡214122 [3]江南大学,工业微生物研究中心,江苏无锡214122

出　　处：《食品与发酵工业》2020年第19期17-22,共6页Food and Fermentation Industries

摘　　要：克雷伯氏菌(Klebsiella pneumoniae)代谢甘油合成1,3-丙二醇(1,3-propanediol,1,3-PDO)的过程中,存在乙酸溢流、TCA循环活性低的问题,影响1,3-PDO合成。该研究对K.pneumoniae中乙醛酸循环抑制因子iclR进行敲除,并过表达TCA循环中琥珀酸脱氢酶基因sdhC和苹果酸脱氢酶基因mdh,缓解乙酰辅酶A节点的碳流溢出。结果表明,敲除iclR后乙酸积累量降低了41%,1,3-PDO产量提高了8%。在K.pLric中单独过表达sdh C或mdh基因,2,3-丁二醇产量分别降低了47%和52%,1,3-PDO产量分别提高了7%和8%。共表达sdh C和mdh基因后,菌株的甘油利用能力增强,1,3-PDO产量比K.pLric提高了11%。5 L发酵罐分批补料发酵结果表明,K.pLric-sdh C-mdh的生物量明显提高,1,3-PDO产量达77.2 g/L,摩尔转化率为0.69 mol/mol。以上结果表明,敲除iclR激活乙醛酸循环、过表达sdh C和mdh强化TCA循环可以弱化乙酸溢流,增强菌株的甘油利用能力,促进合成1,3-PDO。Acetate overflow and low tricarboxylic acid cycle(TCA cycle)activity inhibit the bioproduction of 1,3-propanediol from glycerol by Klebsiella pneumoniae.To relieve the overflow in acetyl-CoA node,iclR encoding isocitrate lyase regulator was deleted,sdhC encoding succinate dehydrogenase and mdh encoding malate dehydrogenase were overexpressed.Deletion of iclR decreased the accumulation of acetate by 41%and increased the 1,3-propanediol titer by 8%.Further overexpression of sdhC or mdh decreased the accumulation of 2,3-butanediol by 47%or 52%and improved the yield of 1,3-propanediol by 7%or 8%.Co-expression of sdhC and mdh improved the glycerol consumption and increased the 1,3-propanediol titer by 11%.The biomass of K.pneumoniae Lric-sdhC-mdh was significantly improved and the 1,3-propanediol titer reached 77.2 g/L with a molar yield of 0.69 mol/moL in fed-batch fermentation.These results indicated that activating glyoxylate bypass by disruption of iclR and reinforcement of the TCA cycle by overexpression of sdhC and mdh decrease acetate accumulation and increase glycerol consumption,which are favorable for the synthesis of 1,3-propanediol.

关 键 词：iclR sdh C MDH 乙醛酸循环 TCA循环 克雷伯氏菌 1 3-丙二醇 

分 类 号：TQ923[轻工技术与工程—发酵工程]