Otten Jonathan K, Zou Yin, Papoutsakis Eleftherios T
Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, United States.
Delaware Biotechnology Institute, University of Delaware, Newark, DE, United States.
Front Bioeng Biotechnol. 2022 Aug 22;10:965614. doi: 10.3389/fbioe.2022.965614. eCollection 2022.
Caproate (hexanoate) and other medium-chain fatty acids are valuable platform chemicals produced by processes utilizing petroleum or plant oil. , growing on short chain alcohols (notably ethanol) and carboxylic acids (such as acetate) is noted for its ability to perform chain elongation to produce 4- to 8-carbon carboxylates. has been studied in monoculture and coculture conditions, which lead to relatively modest carboxylate titers after long fermentation times. To assess the biosynthetic potential of for caproate production from sugars through coculture fermentations, in the absence of monoculture data in the literature suitable for our coculture experiments, we first explored monocultures. Some monocultures achieved caproate titers of 150 to over 200 mM in 40-50 h with a production rate of 7.9 mM/h. Based on that data, we then explored two novel, syntrophic coculture partners for producing caproate from sugars: and . Neither species has been cocultured with before, and both demonstrate promising results. Our experiments of monocultures and - cocultures demonstrate exceptionally high caproate titers (145-200 mM), fast production rates (3.25-8.1 mM/h), and short fermentation times (18-45 h). These results represent the most caproate produced by a coculture in the shortest known fermentation time. We also explored the possibility of heterologous cell fusion between the coculture pairs similar to the results seen previously in our group with and Fusion events were observed only in the - coculture pair, and we offer an explanation for the lack of fusion between and . This work supports the promise of coculture biotechnology for sustainable production of caproate and other platform chemicals.
己酸盐（己酸酯）和其他中链脂肪酸是通过利用石油或植物油的工艺生产的有价值的平台化学品。以能够在短链醇（特别是乙醇）和羧酸（如乙酸盐）上生长并进行链延长以产生4至8个碳原子的羧酸盐而闻名。已在单培养和共培养条件下进行了研究，在长时间发酵后，羧酸盐的滴度相对适中。为了评估通过共培养发酵从糖生产己酸盐的生物合成潜力，由于文献中缺乏适合我们共培养实验的单培养数据，我们首先探索了单培养。一些单培养在40至50小时内实现了150至超过200 mM的己酸盐滴度，生产率为7.9 mM/h。基于该数据，我们随后探索了两种用于从糖生产己酸盐的新型共生共培养伙伴：和。这两个物种以前都没有与共培养过，并且都显示出有希望的结果。我们的单培养和 - 共培养实验证明了极高的己酸盐滴度（145 - 200 mM）、快速的生产率（3.25 - 8.1 mM/h）和较短的发酵时间（18 - 45小时）。这些结果代表了在最短已知发酵时间内共培养产生的最高己酸盐产量。我们还探索了共培养对之间异源细胞融合的可能性，类似于我们小组之前在和中看到的结果。仅在 - 共培养对中观察到融合事件，并且我们对和之间缺乏融合提供了解释。这项工作支持了共培养生物技术在可持续生产己酸盐和其他平台化学品方面的前景。
