Department of Chemical Engineering, Federal University of Sergipe, 49100-000, Sergipe, Brazil.
J Environ Manage. 2022 Mar 1;305:114431. doi: 10.1016/j.jenvman.2022.114431. Epub 2022 Jan 4.
Cellulases are used in various industries, acting efficiently and sustainably in the degradation of cellulose contained in different raw materials and recovering high value products. It is the third largest group of enzymes consumed industrially, as they are required in processes linked to the food, biofuel, textile, cleaning products, among others. However, the main disadvantage in the use of commercial cellulases is the high cost. In this context, the objective of this work was to determine conditions for obtaining more efficient and economical cellulases. For this, the efficiency in obtaining the extracellular cellulases endoglucanase (CMCase) and exoglucanase (FPase) by a fungus Aspergillus niger was investigated using an urban lignocellulosic waste as substrate characterized by tree leaves collected from squares and avenues in urban areas. As urban lignocellulosic waste is an innovative raw material, its chemical composition was determined. This substrate contains 20.36% cellulose and induced the production of cellulases in all fermentation methods, proving to be a promising and sustainable source. The influence of the nutrient medium on CMCase and FPase activities was evaluated for three different sequential fermentation (SF) configurations. Medium 2 provided an increase of up to 100 U/L of CMCase and FPase in relation to medium 1. The interactive effect of pH and moisture content on CMCase e FPase production under SF was studied in a central composite design (CCD). Also, different fermentation methods (solid state, submerged and sequential) were evaluated. The use of SF increased the enzymatic activities of both cellulases by 140% compared to other conventional methods and also stood out in the production of proteins (270.05 μg/mL) and reducing sugars (1.19 mg/mL). The desirability function determined the optimal activities of CMCase and FPase as 413.49 U/L and 230.68 U/L, respectively, obtained from the optimal variables of pH 5.5 and 75% moisture content under SF. The effect of pH and moisture content on the activity of each cellulase was analyzed using the Pareto chart and response surface methodology (RSM). These results revealed favorable strategies for cellulase production, such as the use of urban lignocellulosic waste, SF and ideal operational conditions.
纤维素酶在各个行业中得到广泛应用，能够高效、可持续地降解不同原料中的纤维素，并回收高价值产品。它是工业上消耗的第三大酶类，因为它们在与食品、生物燃料、纺织、清洁产品等相关的过程中是必需的。然而，商业纤维素酶的主要缺点是成本高。在这种情况下，本工作的目的是确定获得更高效、更经济的纤维素酶的条件。为此，研究了一种黑曲霉（Aspergillus niger）利用城市木质纤维素废物作为底物获得胞外纤维素酶内切葡聚糖酶（CMCase）和外切葡聚糖酶（FPase）的效率。该城市木质纤维素废物是一种创新的原料，其化学组成已确定。该底物含有 20.36%的纤维素，并在所有发酵方法中诱导了纤维素酶的产生，证明是一种有前途和可持续的来源。为三种不同的顺序发酵（SF）配置评估了营养培养基对 CMCase 和 FPase 活性的影响。与培养基 1 相比，培养基 2 使 CMCase 和 FPase 的活性提高了高达 100 U/L。在 SF 中，通过中心复合设计（CCD）研究了 pH 和水分含量对 CMCase 和 FPase 生产的交互作用。还评估了不同的发酵方法（固态、浸没和顺序）。与其他常规方法相比，SF 提高了两种纤维素酶的酶活，分别提高了 140%，并且在蛋白质（270.05μg/mL）和还原糖（1.19mg/mL）的生产方面也表现出色。期望函数确定了 CMCase 和 FPase 的最佳活性分别为 413.49 U/L 和 230.68 U/L，这是在 SF 下通过最佳变量 pH 5.5 和 75%水分含量获得的。通过 Pareto 图和响应面法（RSM）分析了 pH 和水分含量对每种纤维素酶活性的影响。这些结果揭示了有利于纤维素酶生产的有利策略，例如使用城市木质纤维素废物、SF 和理想的操作条件。
