探究常压中温下不减小生物质粒度的水稻秸秆预处理方法。以预处理后秸秆保留量(g/g)、预处理秸秆酶解产糖量(g/g)、初始秸秆比产糖量(g/g)为预处理的评估指标。通过单因素实验确定以NaOH为预处理试剂。通过单因素和响应面优化得到预处理的条件为温度55 ℃、时间30 h、质量浓度1.3 g/dL,初始秸秆比产糖量(g/g)为0.271 g/g,与预测值基本一致。对预处理前后的水稻秸秆进行电镜扫描和红外光谱分析,显示预处理打破了水稻秸秆的部分关键结构,使其易于酶解。以预处理前后的水稻秸秆为唯一碳源,里氏木霉为菌种进行液态产酶产糖发酵,发现未处理的水稻秸秆中微生物不能生长,预处理秸秆发酵液中里氏木霉长势良好,发酵5 d,测得滤纸酶活(filter paper activity, FPA)0.522 IU/mL。本研究将为水稻秸秆预处理技术和生物炼制提供一定的参考。
This study aimed to develop a new method for rice straw pretreatment under normal pressures and moderate temperatures without reducing biomass particle size. The evaluation index for analyzing the method included: straw retention (g/g), sugar yield (g/g), and initial straw specific yield of sugar (g/g).The optimal pretreatment conditions were determined by single factor and response surface experiments: using 1.3% (w/v) NaOH as pretreatment reagent and incubating at 55 ℃ for 30 h. Finally, the initial straw specific sugar yield (g/g) was 0.271 g/g. Scanning electron microscope (SEM) and infrared spectrum analysis of rice straw before and after pretreatment showed that the pretreatment broke up some key structures of rice straw, which allows more efficient enzymatic hydrolysis. Trichoderma reesei was used as the enzyme producer and for sugar consumption. The rice straw before or after pretreatment were used as the only carbon source for the fermentation. It was found that Trichoderma reesei in non-treated rice straw-containing media was not able to grow, but grew well in the pretreatment straw media. The FPA enzyme activity reached to 0.522 IU/mL after 5 days of fermentation. This study would provide some references for rice straw pretreatment and biological refining.
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