Butanol toxicity, oxygen sensitivity, and high substrate cost limit wider applications of the traditional Clostridium acetone-butanol-ethanol (ABE) fermentation. In this study, a wild-type Clostridium beijerinckii strain was partnered with an engineered Escherichia coli strain to improve the ABE fermentation through a co-culture. Butanol and butyrate produced by C. beijerinckii were converted into butyl butyrate – a product that can be in situ removed to reduce product toxicity – by expressing a CoA transferase and an alcohol acyltransferase in E. coli. When integrated with a pretreatment technology and using commercial cellulase, the co-culture produced 1280 mg/L butyl butyrate from rice straw in bioreactors, without the need of maintaining a strict anaerobic condition. As a process harnessing both the genetic tractability of E. coli and the superior acid- and alcohol-producing ability of Clostridium, this co-culture fermentation will be useful in producing valuable esters from low-cost waste streams.

丁醇毒性、氧敏感性和高底物成本限制了传统梭菌丙酮-丁醇-乙醇 (ABE) 发酵的更广泛应用。在这项研究中，野生型拜氏梭菌菌株与工程大肠杆菌菌株合作，通过共培养改善 ABE 发酵。通过在大肠杆菌中表达辅酶 A 转移酶和醇酰基转移酶，将拜氏梭菌产生的丁醇和丁酸转化为丁酸丁酯——一种可以原位去除以降低产品毒性的产品. 当与预处理技术相结合并使用商业纤维素酶时，共培养物在生物反应器中从稻草中产生了 1280 mg/L 的丁酸丁酯，而无需维持严格的厌氧条件。作为一种利用大肠杆菌的遗传易处理性和梭状芽胞杆菌卓越的产酸和产醇能力的工艺，这种共培养发酵将有助于从低成本废物流中生产有价值的酯类。