Background The growth of the cellulosic ethanol industry is currently impeded by high production costs. One possible solution is to improve the performance of fermentation itself, which has great potential to improve the economics of the entire production process. Here, we demonstrated significantly improved productivity through application of an advanced fermentation approach, named self-cycling fermentation (SCF), for cellulosic ethanol production. Results The flow rate of outlet gas from the fermenter was used as a real-time monitoring parameter to drive the cycling of the ethanol fermentation process. Then, long-term operation of SCF under anaerobic conditions was improved by the addition of ergosterol and fatty acids, which stabilized operation and reduced fermentation time. Finally, an automated SCF system was successfully operated for 21 cycles, with robust behavior and stable ethanol production. SCF maintained similar ethanol titers to batch operation while significantly reducing fermentation and down times. This led to significant improvements in ethanol volumetric productivity (the amount of ethanol produced by a cycle per working volume per cycle time)-ranging from 37.5 to 75.3%, depending on the cycle number, and in annual ethanol productivity (the amount of ethanol that can be produced each year at large scale)-reaching 75.8 ± 2.9%. Improved flocculation, with potential advantages for biomass removal and reduction in downstream costs, was also observed. Conclusion Our successful demonstration of SCF could help reduce production costs for the cellulosic ethanol industry through improved productivity and automated operation.

中文翻译：

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通过气体流速驱动的自循环发酵提高生物乙醇的生产率。

背景技术纤维素乙醇工业的发展目前受到高生产成本的阻碍。一种可能的解决方案是提高发酵本身的性能，这在提高整个生产过程的经济性方面具有巨大潜力。在这里，我们展示了通过应用一种名为自循环发酵 (SCF) 的先进发酵方法来生产纤维素乙醇，显着提高了生产力。结果发酵罐出口气体流量作为实时监测参数来驱动乙醇发酵过程的循环。然后，通过添加麦角甾醇和脂肪酸改善了SCF在厌氧条件下的长期运行，从而稳定了运行并缩短了发酵时间。最后，一个自动化的 SCF 系统成功运行了 21 个循环，具有稳健的行为和稳定的乙醇生产。SCF 保持与批量操作相似的乙醇滴度，同时显着减少发酵和停机时间。这导致乙醇体积生产力（每个循环时间每个工作体积的循环产生的乙醇量）显着提高 - 范围从 37.5% 到 75.3%，具体取决于循环次数，以及年乙醇生产力（乙醇的量每年可大规模生产）——达到75.8±2.9%。还观察到改进的絮凝作用，具有去除生物质和降低下游成本的潜在优势。