This study reports an enhancement of ethanol yield in Saccharomyces cerevisiae with low-intensity ultrasonic irradiation using fixed mode frequency generated by a self-developed six-frequencies (20, 23, 25, 28, 33, 40 kHz) ultrasonic device in our group. After sonication treatment, the ethanol production potential was determined. Under the optimal conditions of ultrasonic treatment (ultrasonic frequency 28 kHz, power density 180 W/L, and treatment time 24 h), the maximum ethanol yield increased by 34.87% compared to the control. Transcriptome sequencing showed that the ultrasonic treatment had expressional regulations on genes involved in pyruvate metabolism, glycolysis, pentose phosphate pathway, glucose transport, and reducing power production. The quantitative real-time polymerase chain reaction (qRT-PCR) further confirmed the changes in gene expression (up- or down-regulation). Metabolomics revealed that ultrasonic treatments increased intracellular glucose and nicotinamide adenine dinucleotide (NADH) contents, which are key metabolites for ethanol synthesis. Besides, ultrasonic treatments decreased the acetate and its derivatives resulting in lowered reverse consumption of pyruvate and thus promoted ethanol synthesis. These changes in gene expression and metabolites content might be the main reason why the ethanol yield in Saccharomyces cerevisiae increased after ultrasonic irradiation.

本研究报告使用我们组自行开发的六频（20、23、25、28、33、40 kHz）超声波装置产生的固定模式频率进行低强度超声波照射，提高了酿酒酵母的乙醇产量。超声处理后，测定乙醇生产潜力。在最佳超声处理条件下（超声频率28 kHz、功率密度180 W/L、处理时间24 h），最大乙醇产量较对照提高34.87%。转录组测序表明，超声波处理对涉及丙酮酸代谢、糖酵解、磷酸戊糖途径、葡萄糖转运和减少发电的基因有表达调控。实时定量聚合酶链反应（qRT-PCR）进一步证实了基因表达的变化（上调或下调）。代谢组学显示，超声波处理增加了细胞内葡萄糖和烟酰胺腺嘌呤二核苷酸（NADH）的含量，它们是乙醇合成的关键代谢物。此外，超声波处理减少了乙酸及其衍生物，从而降低了丙酮酸的反向消耗，从而促进了乙醇的合成。这些基因表达和代谢物含量的变化可能是超声波照射后酿酒酵母乙醇产量增加的主要原因。