过表达长链鞘氨醇激酶基因LCB4提高酿酒酵母抑制物耐受性

Improvement of inhibitors tolerance of Saccharomyces cerevisiae by overexpressing of long chain sphingoid kinases encoding gene LCB4

摘要:

木质纤维素预处理过程中产生的有毒副产物严重影响了纤维素乙醇发酵，提高酿酒酵母抑制物耐受性是提高纤维素乙醇发酵效率的有效方法。文中通过过表达LCB4基因，研究了重组菌株S288C-LCB4在乙酸、糠醛和香草醛胁迫下的细胞生长和乙醇发酵性能。结果表明，LCB4过表达菌株在分别含有10 g/L乙酸、1.5 g/L糠醛和1 g/L香草醛的平板中生长均优于对照菌株；在分别含有10 g/L乙酸、3 g/L糠醛和2 g/L香草醛的液体乙醇发酵过程中，重组菌株S288C-LCB4乙醇发酵产率分别为0.85 g/(L·h)、0.76 g/(L·h)和1.12 g/(L·h)，比对照菌株提高了34.9%、85.4%和330.8%；且糠醛和香草醛胁迫下发酵时间分别缩短了30 h和44 h。根据发酵终点发酵液代谢物分析发现重组菌株比对照菌株产生了更多甘油、海藻糖和琥珀酸，这些物质有利于增强菌株的抑制物耐受性。综上所述，LCB4基因过表达可显著提高酿酒酵母S288C在乙酸、糠醛和香草醛胁迫下的乙醇发酵性能。

Abstract:

By-products released from pretreatment process of lignocellulose seriously hinder the development of cellulosic fuel ethanol. Therefore, the great way to increase the efficiency of cellulosic ethanol production is improvement of Saccharomyces cerevisiae tolerance to these inhibitors. In this work, the effects of LCB4 gene overexpression on cell growth and ethanol fermentation in S. cerevisiae S288C under acetic acid, furfural and vanillin stresses were studied. Compared to the control strain S288C-HO, the recombinant strain S288C-LCB4 grew better on YPD solid medium containing 10 g/L acetic acid, 1.5 g/L furfural and 1 g/L vanillin. Ethanol yields of recombinant strain S288C-LCB4 were 0.85 g/(L·h), 0.76 g/(L·h) and 1.12 g/(L·h) when 10 g/L acetic acid, 3 g/L furfural and 2 g/L vanillin were supplemented into the fermentation medium respectively, which increased by 34.9%, 85.4% and 330.8% than the control strain S288C-HO. Meanwhile, ethanol fermentation time was reduced by 30 h and 44 h under furfural and vanillin stresses respectively. Further metabolites analysis in fermentation broth showed that the recombinant strain produced more protective compounds, such as glycerol, trehalose and succinic acid, than the control strain, which could be the reason for enhancing strain tolerance to these inhibitors from pretreatment process of lignocellulose. The results indicated that overexpression of LCB4 gene could significantly improve ethanol fermentation in S. cerevisiae S288C under acetic acid, furfural and vanillin stresses.