Secretomic analysis of cheap enzymatic cocktails of Aspergillus niger LBM 134 grown on cassava bagasse and sugarcane bagasse

Currently, agroindustrial wastes are little used for generating value-added products; hence, their use of these waste to produce enzymatic cocktails for the conversion of lignocellulosic biomass to fermentable sugars is a very interesting alternative in the second-generation bioethanol process. The Ascomycota fungus Aspergillus niger LBM 134 produces hydrolytic enzymes in large proportions. In this work, A. niger LBM 134 was grown on sugarcane and cassava bagasses under optimized conditions. To identify the extracellular enzymes involved in the degradation of these agroindustrial wastes, the secretomes of the culture supernatants of the fungus were analyzed and validated by biochemical assays of the enzymatic activities. A. niger LBM 134 secreted higher quantities of xylanases and accessory hemicellulases when it grew on sugarcane bagasse, whereas more cellulases, amylases, and pectinases were secreted when it grew on cassava bagasse. These findings suggest two promising enzyme cocktails for the hydrolysis of lignocellulose carbohydrate polymers to fermentable sugars. These bioinformatic analysis were functional validates through enzymatic biochemical assays that confirm the biotechnological potential of A. niger LBM 134 for the bioconversion of hemicellulosic substrates such as sugarcane and cassava bagasses.当前，农工业废弃物在制备增值产物方面的利用率极低，因此利用此类废弃物生产用于将木质纤维素生物质（lignocellulosic biomass）转化为可发酵糖（fermentable sugars）的复合酶制剂（enzymatic cocktails），是第二代生物乙醇（second-generation bioethanol）生产工艺中极具潜力的替代方案。子囊菌门（Ascomycota）真菌黑曲霉（Aspergillus niger）LBM 134可大量分泌水解酶类。本研究中，黑曲霉LBM 134在优化培养条件下，分别以甘蔗渣与木薯渣为碳源进行培养。为鉴定参与降解此类农工业废弃物的胞外酶，本研究通过酶活性生化实验对该真菌的培养上清液分泌组（secretome）进行了分析与验证。当以甘蔗渣为碳源时，黑曲霉LBM 134分泌的木聚糖酶（xylanases）与辅助半纤维素酶（hemicellulases）含量更高；而以木薯渣为碳源时，其分泌的纤维素酶（cellulases）、淀粉酶（amylases）与果胶酶（pectinases）含量更高。上述研究结果表明，可开发两种极具应用前景的复合酶制剂，用于将木质纤维素类碳水化合物聚合物水解为可发酵糖。本研究通过酶活性生化实验对生物信息学分析结果进行了功能验证，证实了黑曲霉LBM 134在将甘蔗渣、木薯渣等半纤维素底物进行生物转化方面的生物技术应用潜力。