Microbial oil biosynthesis is envisaged as a promising technology for sustainable production of chemicals and fuels. Sugar-based substrates are the most typical carbon sources used for this purpose where metabolic pathways and stoichiometry are well known. However, the use of low-cost substrates is crucial for the economic viability of the process. Volatile fatty acids (VFAs) are considered to be a novel low-cost carbon source for microbial lipid production. They can be utilized by oleaginous yeasts to produce and store fatty acids in form of intracellular lipid bodies. In this work, Yarrowia lipolytica growth and substrate consumption were evaluated using the major VFAs present in anaerobic effluents. Individual VFAs as well as synthetic mixtures were tested at different concentrations to determine uptake rates and potential toxicity. Increasing VFA chain length resulted in greater biomass yield although, when added individually, 4 g Carbon/L VFA (e.g. 6.45 g/L of caproic and 10 g/L of acetic acid) caused inhibitory effects. Remarkably, biomass growth increased by 2.5-fold on real anaerobic fermentation effluent compared with synthetic mixtures. When real digestate was supplemented with synthetic VFAs up to 26.5 g/L, the inhibitory effect of the acids was counterbalanced. The results provided evidence of robustness of Y. lipolytica towards low-cost fermentation effluents and present this yeast as a promising candidate for the sustainable production of microbial oil using real digestates.

中文翻译：

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来自有机废物的挥发性脂肪酸作为解脂耶氏酵母的新型低成本碳源

微生物油生物合成被认为是可持续生产化学品和燃料的有前途的技术。糖基底物是用于此目的的最典型的碳源，其中代谢途径和化学计量学是众所周知的。然而，低成本基材的使用对于该工艺的经济可行性至关重要。挥发性脂肪酸（VFA）被认为是微生物脂质生产的新型低成本碳源。产油酵母可以利用它们以细胞内脂质体的形式生产和储存脂肪酸。在这项工作中，使用厌氧流出物中存在的主要 VFA 评估了解脂耶氏酵母的生长和底物消耗。在不同浓度下对单个 VFA 以及合成混合物进行了测试，以确定吸收率和潜在毒性。增加 VFA 链长度会导致更高的生物质产量，尽管单独添加时，4 g 碳/L VFA（例如 6.45 g/L 己酸和 10 g/L 乙酸）会引起抑制作用。值得注意的是，与合成混合物相比，真正的厌氧发酵流出物的生物量增长增加了 2.5 倍。当真正的消化物中添加了高达 26.5 g/L 的合成 VFA 时，酸的抑制作用被抵消了。结果提供了解脂耶氏酵母对低成本发酵流出物的稳健性的证据，并将这种酵母作为使用真正消化物可持续生产微生物油的有希望的候选者。与合成混合物相比，真正的厌氧发酵流出物的生物量增长增加了 2.5 倍。当真正的消化物中添加了高达 26.5 g/L 的合成 VFA 时，酸的抑制作用被抵消了。结果提供了解脂耶氏酵母对低成本发酵流出物的稳健性的证据，并将这种酵母作为使用真正消化物可持续生产微生物油的有希望的候选者。与合成混合物相比，真正的厌氧发酵流出物的生物量增长增加了 2.5 倍。当真正的消化物中添加了高达 26.5 g/L 的合成 VFA 时，酸的抑制作用被抵消了。结果提供了解脂耶氏酵母对低成本发酵流出物的稳健性的证据，并将这种酵母作为使用真正消化物可持续生产微生物油的有希望的候选者。