Dien Bruce S, Ximenes Eduardo A, O'Bryan Patricia J, Moniruzzaman Mohammed, Li Xin-Liang, Balan Venkatesh, Dale Bruce, Cotta Michael A
National Center for Agricultural Utilization Research, USDA, Agricultural Research Service, 1815 North University Street, Peoria, IL 61604, United States.
Bioresour Technol. 2008 Aug;99(12):5216-25. doi: 10.1016/j.biortech.2007.09.030. Epub 2007 Nov 8.
Dried distillers' grains with solubles (DDGS), a co-product of corn ethanol production, was investigated as a feedstock for additional ethanol production. DDGS was pretreated with liquid hot-water (LHW) and ammonia fiber explosion (AFEX) processes. Cellulose was readily converted to glucose from both LHW and AFEX treated DDGS using a mixture of commercial cellulase and beta-glucosidase; however, these enzymes were ineffective at saccharifying the xylan present in the pretreated DDGS. Several commercial enzyme preparations were evaluated in combination with cellulase to saccharify pretreated DDGS xylan and it was found that adding commercial grade (e.g. impure) pectinase and feruloyl esterase (FAE) preparations were effective at releasing arabinose and xylose. The response of sugar yields for pretreated AFEX and LHW DDGS (6wt%/solids) were determined for different enzyme loadings of FAE and pectinase and modeled as a response surfaces. Arabinose and xylose yields rose with increasing FAE and pectinase enzyme dosages for both pretreated materials. When hydrolyzed at 20wt%/solids with the same blend of commercial enzymes, the yields were 278 and 261g sugars (i.e. total of arabinose, xylose, and glucose) per kg of DDGS (dry basis, db) for AFEX and LHW pretreated DDGS, respectively. The pretreated DDGS's were also evaluated for fermentation using Saccharomyces cerevisiae at 15wt%/solids. Pretreated DDGS were readily fermented and were converted to ethanol at 89-90% efficiency based upon total glucans; S. cerevisiae does not ferment arabinose or xylose.
干酒糟及其可溶物（DDGS）是玉米乙醇生产的一种副产品，被作为额外乙醇生产的原料进行了研究。DDGS采用液态热水（LHW）和氨纤维爆破（AFEX）工艺进行预处理。使用商业纤维素酶和β-葡萄糖苷酶的混合物，纤维素能很容易地从经LHW和AFEX处理的DDGS中转化为葡萄糖；然而，这些酶在糖化预处理DDGS中存在的木聚糖方面效果不佳。评估了几种商业酶制剂与纤维素酶联合使用对预处理DDGS木聚糖进行糖化的效果，发现添加商业级（如不纯的）果胶酶和阿魏酸酯酶（FAE）制剂在释放阿拉伯糖和木糖方面是有效的。针对FAE和果胶酶的不同酶负载量，测定了预处理AFEX和LHW DDGS（6wt%/固体）的糖产率响应，并将其建模为响应面。对于两种预处理材料，阿拉伯糖和木糖产率均随着FAE和果胶酶剂量的增加而提高。当以20wt%/固体用相同的商业酶混合物水解时，AFEX和LHW预处理DDGS每千克DDGS（干基，db）的糖产率（即阿拉伯糖、木糖和葡萄糖的总量）分别为278克和261克。还对预处理的DDGS进行了在15wt%/固体下使用酿酒酵母进行发酵的评估。预处理的DDGS易于发酵，基于总葡聚糖，其转化为乙醇的效率为89 - 90%；酿酒酵母不发酵阿拉伯糖或木糖。
