Praj-Matrix - R&D Centre (Division of Praj Industries Limited) 402/403/1098, Urawade, Pirangut, Mulshi, Pune, 412115, India.
Department of Technology, Savitribai Phule Pune University, Ganeshkhind, Pune, 411007, India.
Appl Microbiol Biotechnol. 2019 Jan;103(2):1031-1042. doi: 10.1007/s00253-018-9532-1. Epub 2018 Nov 28.
The ever-increasing demand of energy has made it imperative to increase the production of renewable fuels like ethanol. Many studies have reported increase in ethanol production by reducing fermentation by-products like glycerol. Deletion of structural genes like gpd1and gpd2 leads to an increase in ethanol by reducing glycerol; however, it makes the yeast osmosensitive that is not desirable for industrial strains. In this study, genes in the HOG pathway which regulates glycerol synthesis in Saccharomyces cerevisiae were targeted for improving ethanol yields in fermentation of sugarcane molasses. Deletion strains of ssk1, hot1, and smp1 were tested and they did not show osmosensitivity. Δssk1 and Δsmp1 recombinant strains showed consistent improved ethanol yields. As a result, a double-deletion strain, Δssk1Δsmp1, was also constructed, which showed a synergistic effect leading to 6% increase in ethanol yield and 35% decrease in glycerol yield. It was also observed that there was a significant decrease in acetic acid yields of all the recombinant strains. Overall, the study demonstrates an industrially viable technique of engineering the HOG pathway resulting in decrease of glycerol and no loss of osmotolerance. These S. cerevisiae strains showed a significant increase in ethanol yields.
不断增长的能源需求使得增加可再生燃料（如乙醇）的产量势在必行。许多研究报告称，通过减少甘油等发酵副产物，可以提高乙醇的产量。删除 gpd1 和 gpd2 等结构基因可以通过减少甘油来提高乙醇产量；然而，这会使酵母对渗透压敏感，这对于工业菌株来说是不理想的。在这项研究中，针对调控酿酒酵母甘油合成的 HOG 途径中的基因，旨在提高甘蔗废糖蜜发酵中的乙醇产量。测试了 ssk1、hot1 和 smp1 的缺失菌株，它们没有表现出渗透压敏感性。Δssk1 和 Δsmp1 重组菌株表现出一致的乙醇产量提高。因此，还构建了一个双缺失菌株 Δssk1Δsmp1，它表现出协同作用，导致乙醇产量提高 6%，甘油产量降低 35%。还观察到所有重组菌株的乙酸产量都有显著下降。总的来说，该研究展示了一种可行的工程 HOG 途径的工业技术，可降低甘油含量，同时保持渗透压耐受性。这些酿酒酵母菌株的乙醇产量显著提高。
