Adding value to lignocellulosic wastes via their use for endoxylanase production by <i>Aspergillus</i> fungi

Agroforestry industries in the world generate lignocellulosic wastes that can be a huge problem of pollution, or the wastes can be used for different biotechonological applications such as substrates for microorganism growth and enzyme production. Fungi such as <i>Aspergillus niger</i> can grow in almost every substrate and produce hydrolytic enzymes such as endoxylanases, giving added value to agroforestry wastes generated by industries in the northeast of Argentina. In this context, the aim of this work was to use agroforestry wastes as substrates for the production of endoxylanases by <i>Aspergillus niger</i> and to optimize nitrogen sources and physical variables for the highest endoxylanase activity. <i>A. niger</i> LBM 055 and <i>A. niger</i> LBM 134 produced high endoxylanase levels when they were grown with sugarcane and cassava bagasses as carbon sources. <i>A. niger</i> LBM 134 reached the highest endoxylanase activity when nitrogen sources and physical variables were optimized. The fungus exhibited up to 110 U mL⁻¹ of endoxylanase activity when it was grown with sugarcane bagasse and more than 160 U mL⁻¹ with cassava bagasse. Therefore, endoxylanase production was optimized using agricultural bagasses and cost 20 times less than enzyme production using synthetic xylan.全球农林业产业会产生木质纤维素废弃物，这类废弃物既可能引发严重的污染问题，也可应用于多种生物技术场景，例如用作微生物生长基质与酶制剂生产原料。黑曲霉（Aspergillus niger）等真菌几乎可在各类基质上生长，并能产生内切木聚糖酶等水解酶，为阿根廷东北部产业产生的农林业废弃物赋予附加价值。在此背景下，本研究的目标是以农林业废弃物为基质，利用黑曲霉（Aspergillus niger）生产内切木聚糖酶，并优化氮源与物理参数以实现最高的内切木聚糖酶活性。当以甘蔗渣与木薯渣作为碳源时，黑曲霉LBM 055与黑曲霉LBM 134均可产生较高水平的内切木聚糖酶。经氮源与物理参数优化后，黑曲霉LBM 134的内切木聚糖酶活性达到峰值。当以甘蔗渣为培养基质时，该真菌的内切木聚糖酶活性可达110 U mL⁻¹；以木薯渣为基质时，活性超过160 U mL⁻¹。综上，本研究通过利用农业渣类优化了内切木聚糖酶的生产工艺，其成本仅为使用合成木聚糖进行酶制剂生产的二十分之一。