杨木屑低浓度硫酸中温预处理提取木糖及其发酵

Extraction and Fermentation of Xylose from Poplar Sawdust by Hot Sulfuric Acid Pretreatment at Low Concentration

低酸中温预处理可选择性地水解溶出杨木屑中的木糖。正交试验结果显示,影响木糖提取得率的强度顺序为反应温度、固液比、反应时间和硫酸质量分数,影响抑制物产量的主要因素为反应温度和固液比,硫酸质量分数和反应时间的影响较弱。在预处理过程中生成的主要抑制物为乙酸,其次为甲酸和糠醛。基于技术经济分析,可采用100℃、2.0%硫酸、固液比1∶15(g∶mL)预处理杨木屑10 h,木糖和葡萄糖提取得率分别达74.1%和3.0%。通过细胞回用和驯化可以提高Candida tropicalis NL02发酵杨木屑提取液的生产性能,在含有乙酸3.53 g/L、甲酸2.57 g/L、木糖53.40 g/L和葡萄糖7.09 g/L的提取液中发酵20 h,木糖利用率达85.4%,乙酸和甲酸消耗率分别为52.9%和100%,可生成木糖醇约35.12 g/L和乙醇7.67 g/L,木糖醇和乙醇产率分别达到77.0%和31.4%。

Xylose was selectively hydrolyzed and extracted from poplar sawdust by hot sulfuric acid pretreatment at low concentration（HSAP）.The orthogonal test showed the impact strength of main processing parameters on xylose extraction was descending as follows： temperature,the solid-to-liquid ratio（SLR）,sulfuric acid concentration（SAC） and reaction time（RT）.The total inhibitors production was affected mainly by temperature and SLR,while,SAC and RT had little effects on it.Acetic acid came from poplar sawdust as the first major inhibitor during HSCP and the secondary were formic acid and furfural.The optimum HSCP condition was selected according to techno-economical analysis,in which about 74.1 % xylose and 3.0 % glucose were extracted from poplar sawdust after 10 h at 100 ℃,2.0 % SA and SLR of 1∶15.The fermentability of Candida tropicalis NL02 was improved by yeast recycling and domestication in the extracted solution from poplar sawdust by HSCP.In the extracted solution containing 3.53 g/L acetic acid,2.57 g/L formic acid 53.40 g/L xylose and 7.09 g/L glucose,the yeast could use up 85.4 % xylose,52.9 % acetic acid and 100 % formic acid,and produced 35.12 g/L xylitol and 7.67 g/L ethanol at the yield of 77.0 % and 31.4 %,respectively.