葡萄糖脱氢酶基因的缺失对Acetobacter sp.碳源代谢及3-羟基丙酸合成的影响  

Effects of glucose dehydrogenase gene knock-out in Acetobacter sp. on the metabolism of carbon sources and the synthesis of 3-hydroxypropionic acid

作　　者：操小超 孙雷 宗红 陆信曜 方慧英 诸葛斌 CAO Xiaochao;SUN Lei;ZONG Hong;LU Xinyao;FANG Huiying;ZHUGE Bin(Key Laboratory of Carbohydrate Chemistry and Biotechnology,Mimstry of Education,School of Biotechnology,Jiangnan University,Wuxi 214122,China;Key Laboratory of Industrial Biotechnology,Ministry of Education,Jiangnan University,Laboratory of Industrial Microorganisms,School of Biotechnology,Jiangnan University,Wuxi 214122,China)

机构地区：[1]江南大学糖化学与生物技术教育部重点实验室,无锡214122 [2]江南大学工业生物技术教育部重点实验室,生物工程学院,工业微生物研究中心,无锡214122

出　　处：《应用与环境生物学报》2018年第6期1307-1311,共5页Chinese Journal of Applied and Environmental Biology

基　　金：江苏省自然科学基金项目(BK20140134)资助.

摘　　要：3-羟基丙酸(3-HP)是一种新兴的高附加值平台化合物,醋酸杆菌(Acetobacter sp.)可高效催化1,3-丙二醇(1,3-PDO)合成3-HP,但其膜上脱氢酶亦可将葡萄糖氧化使培养液酸化,菌体生长受限导致生物量较低.利用同源重组技术对葡萄糖脱氢酶(GDH)基因gdh进行敲除,并考察该基因缺失对细胞生长、碳源代谢及3-HP合成的影响. gdh基因敲除后混合(葡萄糖、甘油)碳源培养条件下菌体量较野生菌提高了1.72倍;碳流分析显示葡萄糖在膜上被GDH氧化生成葡萄糖酸,大部分葡萄糖酸最终被氧化为2-酮基葡萄糖酸,少量经戊糖磷酸途径(PPP)途径被分解,而甘油经磷酸化后进入中心代谢途径或糖异生途径.本研究表明gdh基因敲除后混合碳源培养可大幅度提高菌体量且可以保证较高的催化合成3-HP性能,可为改善醋酸菌碳源利用及催化性能提供理论基础.3-Hydroxypropionic acid (3-HP) is an emerging platform chemical with a high added-value. Resting cells of Acetobacter sp. can efficiently catalyze 1,3-propanediol (1,3-PDO) to 3-HP. Glucose is oxidized by the membrane-bound dehydrogenase, resulting in an acidic environment that inhibits cell growth and reduces the biomass. We deleted the gdh gene for glucose dehydrogenase (GDH), and investigated the effects on cell growth, carbon metabolism, and 3-HP production. The gdh gene knocked-out showed a 1.72-fold increase in biomass in the mixed medium containing glucose and glycerol. A carbon flux analysis showed that glucose was converted to gluconic acid by GDH, followed by an oxidation to 2-ketogluconic acid. In addition, a small percentage of the gluconic acid was degraded via the pentose phosphate pathway. Glycerol was phosphorylated and entered the central pathway (gluconeogenesis). Results indicate that the deletion of gdh can effectively promote higher cell densities and improve the catalytic performance for the production of 3-HP, and thus provide a theoretical reference for improving the carbon source utilization and the catalytic performance of acetic acid bacteria.

关 键 词：醋酸杆菌 3-羟基丙酸 葡萄糖脱氢酶 糖异生 2-酮基葡萄糖酸 

分 类 号：Q78[生物学—分子生物学] TQ921[轻工技术与工程—发酵工程]