Adding value to lignocellulosic wastes via their use for endoxylanase production by Aspergillus fungi

ABSTRACT

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 Aspergillus niger 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 Aspergillus niger and to optimize nitrogen sources and physical variables for the highest endoxylanase activity. A. niger LBM 055 and A. niger LBM 134 produced high endoxylanase levels when they were grown with sugarcane and cassava bagasses as carbon sources. A. niger 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.

KEYWORDS:

• Aspergillus niger
• cassava bagasse
• endoxylanases
• eucalyptus sawdust
• pine sawdust
• sugarcane bagasse

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Funding

This work has been possible thanks to support from the Consejo Nacional de Investigaciones Científicas & Técnicas (CONICET) and a project funded by the Secretaría General de Ciencia & Tecnología, Universidad Nacional de Misiones (SGCyT–UNaM).