Flores Andrew D, Ayla E Zeynep, Nielsen David R, Wang Xuan
Chemical Engineering, School for Engineering of Matter, Transport, and Energy , Arizona State University , ECG 301, 501 E. Tyler Mall , Tempe , Arizona 85287 , United States.
School of Life Sciences , Arizona State University , 427 E. Tyler Mall , Tempe , Arizona 85287 , United States.
ACS Synth Biol. 2019 May 17;8(5):1089-1099. doi: 10.1021/acssynbio.9b00007. Epub 2019 Apr 22.
Fermentation of lignocellulosic sugar mixtures is often suboptimal due to inefficient xylose catabolism and sequential sugar utilization caused by carbon catabolite repression. Unlike in conventional applications employing a single engineered strain, the alternative development of synthetic microbial communities facilitates the execution of complex metabolic tasks by exploiting the unique community features, including modularity, division of labor, and facile tunability. A series of synthetic, catabolically orthogonal coculture systems were systematically engineered, as derived from either wild-type Escherichia coli W or ethanologenic LY180. Net catabolic activities were effectively balanced by simple tuning of the inoculum ratio between specialist strains, which enabled coutilization (98% of 100 g L total sugars) of glucose-xylose mixtures (2:1 by mass) for both culture systems in simple batch fermentations. The engineered ethanologenic cocultures achieved ethanol titer (46 g L), productivity (488 mg L h), and yield (∼90% of theoretical maximum), which were all significantly increased compared to LY180 monocultures.
由于木糖分解代谢效率低下以及碳分解代谢物阻遏导致的顺序性糖类利用，木质纤维素糖混合物的发酵往往并非最佳状态。与采用单一工程菌株的传统应用不同，合成微生物群落的替代开发通过利用独特的群落特征，包括模块化、分工和易于调节性，促进了复杂代谢任务的执行。一系列合成的、分解代谢正交的共培养系统被系统地构建，其源自野生型大肠杆菌W或产乙醇的LY180。通过简单调节专业菌株之间的接种比例，有效地平衡了净分解代谢活性，这使得两种培养系统在简单分批发酵中能够共同利用（质量比为2:1）葡萄糖 - 木糖混合物（总糖含量为100 g/L的98%）。工程化的产乙醇共培养物实现了乙醇滴度（46 g/L）、生产率（488 mg/L·h）和产率（约为理论最大值的90%），与LY180单培养物相比均显著提高。
