耐高温东方伊萨酵母乙醇发酵特性

    Ethanol fermentation characteristics of thermotolerant Issatchenkia orientalis

    • 摘要: 燃料乙醇作为一种可再生清洁能源,越来越受到人们的广泛关注,选育出一株耐高温乙醇发酵菌株对于提高乙醇发酵效率、降低能耗和生产成本具有重要意义。该文对分离自烟叶腐解物中的耐高温乙醇发酵菌株HN-1进行生理生化特性试验及分子生物学鉴定,并对其发酵特性进行初步研究。结果表明:HN-1菌株为东方伊萨酵母,能够利用葡萄糖和果糖发酵生产乙醇,但不能利用木糖、半乳糖等。该菌株的最适生长温度为38℃,乙醇发酵的合适温度范围为38~45℃,且随着发酵温度的升高,乙醇生成速率加快,发酵时间缩短。38℃乙醇发酵的最适葡萄糖浓度为120 g/L,乙醇产量为58.19 g/L,乙醇产率为0.460 g/g。利用玉米秸秆水解液发酵,乙醇产量为20.74 g/L,乙醇产率为0.468 g/g,达到葡萄糖理论转化率的91.6%。该研究为生物乙醇的高温发酵提供了宝贵的菌种资源和技术支撑。

       

      Abstract: Abstract: As a renewable and clean energy, bio-ethanol has been received widespread attention in recent years. Ethanol fermentation at high temperature can reduce the consumption of cooling water and energy in the process of fermentation, it also solve the problems caused by saccharification and uncontrolled fermentation temperature, resulting in the simultaneous saccharification and fermentation of cellulosic ethanol. Therefore, the fermentation period can be shorten and the production cost be reduced. A thermotolerant yeast strain HN-1 isolated from rotting tobacco leaves was identified and its ethanol fermentation characteristics was investigated in this study. The phylogenetic analysis indicated that phylogenetic phylogenetistrain HN-1 behaved like Issatchenkia orientalis. This strain useed glucose and D-fructose but could not use xylose, maltose, lactose, sucrose, starch and cellobiose as sole carbon source to produce ethanol. When HN-1 was cultivated in 50 g/L glucose liquid medium, the highest biomass was obtained at 35 and 38℃. Increasing the cultivation temperature to 42 and 45℃ decreased the biomass growth and intensified the cell death. There was no major difference between ethanol productions (21.43~23.12 g/L) fermented at 35~45℃ from 50 g/L glucose. When increasing the fermentation temperature, the ethanol productivity was increased from 0.31 g/(L·h) at 35℃ to 0.65 g/(L·h) at 45℃ after 24h fermentation. The fermentation time was shortened. When the fermentation was conducted at 38℃, 28.77, 43.21, 58.19 and 59.53 g/L ethanol were produced from 60, 90, 120 and 150 g/L glucose with yields of 0.457, 0.468, 0.460 and 0.386 g/g and productivities of 0.38, 0.39, 0.48 and 0.40 g/(L·h) The results also indicated that fed batch fermentation could not enhance the ethanol production. Strain HN-1 could utilize corn straw hydrolysate with 43.08 g/L glucose and 27.13 g/L xylose to produce 20.74 g/L ethanol. The glucose conversion rate was 0.468 g/g, which was 91.6% of the theoretical yield. Noxylose was utilized during the fermentation. This research provides a valuable thermotolerant strain. It is expected that it will be beneficial for industrialized production of bio-ethanol with high temperature fermentation.

       

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