Hocq Rémi, Sauer Michael
CD-Laboratory for Biotechnology of Glycerol, BOKU-University of Natural Resources and Life Sciences, Vienna, Austria.
University of Natural Resources and Life Sciences, Vienna, Department of Biotechnology, Institute of Microbiology and Microbial Biotechnology, Muthgasse 18, 1190 Vienna, Austria.
FEMS Microbes. 2022 Apr 19;3:xtac013. doi: 10.1093/femsmc/xtac013. eCollection 2022.
Converting plant biomass into biofuels and biochemicals microbial fermentation has received considerable attention in the quest for finding renewable energies and materials. Most approaches have so far relied on cultivating a single microbial strain, tailored for a specific purpose. However, this contrasts to how nature works, where microbial communities rather than single species perform all tasks. In artificial coculture systems, metabolic synergies are rationally designed by carefully selecting and simultaneously growing different microbes, taking advantage of the broader metabolic space offered by the use of multiple organisms. 1-propanol and 2-propanol, as biofuels and precursors for propylene, are interesting target molecules to valorize plant biomass. Some solventogenic can naturally produce 2-propanol in the so-called Isopropanol-Butanol-Ethanol (IBE) fermentation, by coupling 2-propanol synthesis to acetate and butyrate reduction into ethanol and 1-butanol. In this work, we hypothesized propanoate would be converted into 1-propanol by the IBE metabolism, while driving at the same time 2-propanol synthesis. We first verified this hypothesis and chose two propionic acid bacteria (PAB) strains as propanoate producers. While consecutive PAB and IBE fermentations only resulted in low propanol titers, coculturing and at various inoculation ratios yielded much higher solvent concentrations, with as much as 21 g/l of solvents (58% increase compared to monoculture) and 12 g/l of propanol (98% increase). Taken together, our results underline how artificial cocultures can be used to foster metabolic synergies, increasing fermentative performances and orienting the carbon flow towards a desired product.
将植物生物质转化为生物燃料和生物化学品——微生物发酵在寻找可再生能源和材料的过程中受到了广泛关注。迄今为止，大多数方法都依赖于培养单一的微生物菌株，这种菌株是为特定目的量身定制的。然而，这与自然的运作方式形成了对比，在自然中，执行所有任务的是微生物群落而非单一物种。在人工共培养系统中，通过精心选择并同时培养不同的微生物，利用多种生物体提供的更广阔代谢空间，合理设计代谢协同作用。1-丙醇和2-丙醇作为生物燃料和丙烯的前体，是使植物生物质增值的有趣目标分子。一些产溶剂菌在所谓的异丙醇-丁醇-乙醇（IBE）发酵中可以通过将2-丙醇合成与将乙酸盐和丁酸盐还原为乙醇和1-丁醇相偶联，从而自然产生2-丙醇。在这项工作中，我们假设丙酸会通过IBE代谢转化为1-丙醇，同时推动2-丙醇的合成。我们首先验证了这一假设，并选择了两种丙酸杆菌（PAB）菌株作为丙酸盐生产者。虽然连续的PAB和IBE发酵仅产生了较低的丙醇滴度，但以不同接种比例将它们共培养可产生更高的溶剂浓度，溶剂含量高达21 g/l（比单培养增加了58%），丙醇含量为12 g/l（增加了98%）。综上所述，我们的结果强调了人工共培养如何可用于促进代谢协同作用，提高发酵性能并使碳流导向所需产物。
