The production of high-activity β-glucosidase at low cost is essential to increase the efficiency of cellulose hydrolysis, necessary for the economically feasible production of biofuels from the conversion of renewable lignocellulosic resources, specifically agricultural waste. In this work, the Aspergillus niger CDBB-H-175 strain was used for the production of extracellular β-glucosidase. In the first stage of this work, the production of β-glucosidase was carried out in a shake flask, using different carbon sources in order to evaluate the effect of the substrate on enzyme activity; in this way, it was determined that the best substrate is maltose, obtaining 2954 U/ml of β-glucosidase activity at 31 days of culture. In the second stage, a laboratory-scale study was done using two discontinuous bioreactor systems for submerged fermentation, stirred tank and airlift, using maltose, sucrose, and glucose as a carbon source. The results showed that β-glucosidase with the highest enzymatic activity (3122 U/ml at 192 h of fermentation) was produced at uncontrolled pH conditions in an airlift bioreactor with maltose. In a third stage, using an airlift bioreactor with maltose, an orthogonal experimental design L₄ with three factors was applied: pH, aeration, and maltose concentration. The aeration was of utmost importance to guarantee a better enzymatic expression, and acidification of the culture medium during the fermentation process was another necessary condition for a greater enzymatic production.

中文翻译：

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黑曲霉CDBB-H-175深层发酵生产β-葡萄糖苷酶

以低成本生产高活性 β-葡萄糖苷酶对于提高纤维素水解效率至关重要，这对于从可再生木质纤维素资源（特别是农业废物）的转化以经济可行的方式生产生物燃料是必不可少的。在这项工作中，黑曲霉CDBB-H-175菌株用于生产细胞外β-葡萄糖苷酶。在这项工作的第一阶段，β-葡萄糖苷酶的生产是在摇瓶中进行的，使用不同的碳源来评估底物对酶活性的影响；这样确定最好的底物是麦芽糖，培养31天得到2954 U/ml的β-葡萄糖苷酶活性。在第二阶段，使用麦芽糖、蔗糖和葡萄糖作为碳源，使用两个不连续的生物反应器系统进行了实验室规模的研究，用于深层发酵、搅拌罐和气升。结果表明，在具有麦芽糖的气升式生物反应器中，在不受控制的 pH 条件下产生了具有最高酶活性的 β-葡萄糖苷酶（发酵 192 小时时为 3122 U/ml）。在第三阶段，₄应用了三个因素：pH、曝气和麦芽糖浓度。通气对于保证更好的酶表达至关重要，发酵过程中培养基的酸化是提高酶产量的另一个必要条件。