Alkali-Based AFEX Pretreatment for the Conversion of Sugarcane Bagasse and Cane Leaf residues to Ethanol
Alkali-Based AFEX Pretreatment for the Conversion of Sugarcane Bagasse and Cane Leaf residues to Ethanol
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DOI：
10.1002/bit.22824
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发表时间：
2010-10-15
影响因子：
3.8
通讯作者：
Balan, Venkatesh
中科院分区：
文献类型：
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作者：
Krishnan, Chandraraj;Sousa, Leonardo da Costa;Balan, Venkatesh
甘蔗是世界上热带气候地区种植的主要农作物之一。每生产一吨原料甘蔗，在榨汁后产生130公斤干重的甘蔗渣，在收获后产生250公斤干重的甘蔗叶渣。世界甘蔗年产量约为16亿吨，产生279百万吨的生物质残渣（甘蔗渣和甘蔗叶物质），可用于纤维素乙醇生产。在这里，我们研究了生产纤维素乙醇从甘蔗渣和甘蔗叶渣使用碱预处理：氨纤维膨胀（AFEX）。AFEX预处理通过破坏酯键和其他木质素碳水化合物复合物（LCC）键来改善纤维素和半纤维素在水解期间对酶的可及性，并且发现通过该过程产生的糖是高度可发酵的。纤维素酶对AFEX预处理的甘蔗渣和甘蔗叶渣的最大葡聚糖转化率接近85%。在酶水解过程中补充半纤维素酶可将木聚糖转化率提高至95- 98%。木聚糖酶补充也有助于葡聚糖转化的边际改善。AFEX处理的甘蔗叶渣被发现有一个更大的酶消化比AFEX处理的甘蔗渣。利用重组酿酒酵母（424 A LNH-ST）对经AFEX处理的甘蔗渣和甘蔗叶渣的高固体负荷（6%葡聚糖）水解产生的葡萄糖和木糖进行共发酵，产生34-36 g/L的乙醇，理论产率为92%。这些结果表明AFEX预处理是将甘蔗渣和甘蔗叶渣转化为纤维素乙醇的可行方法。Biotechnol. Bioeng. 2010; 107：441-450。(C)2010 Wiley Periodicals，Inc.
Sugarcane is one of the major agricultural crops cultivated in tropical climate regions of the world. Each tonne of raw cane production is associated with the generation of 130 kg dry weight of bagasse after juice extraction and 250 kg dry weight of cane leaf residue postharvest. The annual world production of sugarcane is similar to 1.6 billion tones, generating 279 MMT tones of biomass residues (bagasse and cane leaf matter) that would be available for cellulosic ethanol production. Here, we investigated the production of cellulosic ethanol from sugar cane bagasse and sugar cane leaf residue using an alkaline pretreatment: ammonia fiber expansion (AFEX). The AFEX pretreatment improved the accessibility of cellulose and hemicelluloses to enzymes during hydrolysis by breaking down the ester linkages and other lignin carbohydrate complex (LCC) bonds and the sugar produced by this process is found to be highly fermentable. The maximum glucan conversion of AFEX pretreated bagasse and cane leaf residue by cellulases was similar to 85%. Supplementation with hemicellulases during enzymatic hydrolysis improved the xylan conversion up to 95-98%. Xylanase supplementation also contributed to a marginal improvement in the glucan conversion. AFEX-treated cane leaf residue was found to have a greater enzymatic digestibility compared to AFEX-treated bagasse. Co-fermentation of glucose and xylose, produced from high solid loading (6% glucan) hydrolysis of AFEX-treated bagasse and cane leaf residue, using the recombinant Saccharomyces cerevisiae (424A LNH-ST) produced 34-36 g/L of ethanol with 92% theoretical yield. These results demonstrate that AFEX pretreatment is a viable process for conversion of bagasse and cane leaf residue into cellulosic ethanol. Biotechnol. Bioeng. 2010; 107: 441-450. (C) 2010 Wiley Periodicals, Inc.