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玉米秸秆是我国主要的农业废弃物之一,在木质纤维素乙醇领域具有广阔的应用前景。而玉米秸秆预处理和酶法糖化成本过高是目前工艺中的重点和难点之一。从4种纤维素降解酶制剂中优选出对中性汽爆玉米秸秆有最佳协同效果的木霉和黑曲霉纤维素酶制剂(6∶4体积比混合)。在此基础上,评估了木聚糖酶、β-葡萄糖苷酶、β-葡聚糖酶、漆酶、锰过氧化物酶等酶制剂,聚乙二醇-4000、吐温-80、牛血清白蛋白等非酶因子对糖化效率的影响,得到了一组高效协同降解汽爆玉米秸秆的复合酶体系,并获得了适宜的糖化工艺。结果表明,以每克中性汽爆预处理的玉米秸秆为底物,加入10FPU木霉/曲霉混合酶液,并添加1000IU的木聚糖酶和0.05 gPEG4000,于50℃/150 r.min-1条件下水解144 h,糖化液中纤维二糖、葡萄糖和木糖的浓度分别达到8.4、25.1、15.5 g.L-1,总转化率、纤维素、半纤维素的转化率分别可以达到71.1%、81.5%和55.3%。糖化产物中六碳糖和五碳糖总浓度达到49 g.L-1。
Corn stalk is one of the main agricultural wastes in our country, and has broad application prospects in the field of lignocellulosic ethanol. The pretreatment of corn stalks and high cost of enzymatic saccharification is one of the key and difficult points in the current process. Trichoderma and Aspergillus niger cellulase preparation (6: 4 volume ratio mixing) with the best synergistic effect on neutral steam explosion corn stover was selected from the four cellulose degrading enzyme preparations. On this basis, enzyme preparations such as xylanase, β-glucosidase, β-glucanase, laccase and manganese peroxidase, polyethylene glycol-4000, Tween-80, Serum albumin and other non-enzymatic factors on the efficiency of saccharification, obtained a group of highly efficient synergistic degradation steam explosion corn stalk complex enzyme system, and access to the appropriate saccharification process. The results showed that 10 FPU Trichoderma / Aspergillus mixed enzyme solution was added per gram neutral steam explosion pretreated corn stalks and 1000 IU xylanase and 0.05 g PEG4000 were added at 50 ℃ / 150 r.min- 1, the concentration of cellobiose, glucose and xylose reached 8.4, 25.1 and 15.5 gL-1, respectively. The total conversion, the conversion of cellulose and hemicellulose reached 71.1% 81.5% and 55.3%. The total concentration of hexose and pentose in the saccharification product reached 49 g · L -1.