Thermostable Fungal Xylanase as a Supplemental Additive for Commercial Cocktails

Abstract

Carlos Junior de Assis Estevao, Lucas Filipe Almeida, Luiz Vinicius de Souza Arruda, Joao Batista de Souza, Valeria Monteze Guimaraes, Rafael Ferreira Alfenas and Gabriela Piccolo Maitan Alfenas

Enzymes are crucial in acquiring valuable biotechnological products, such as fermentable sugars, from alternative carbon sources. Lignocellulosic biomass, often derived from agro-industrial wastes, serves as a renewable source for second-gener- ation (2G) ethanol production employing cellulolytic and hemicellulolytic enzymes in the saccharification process, releasing glucose for alcoholic fermentation. Thus, there is a growing demand for novel catalysts that act in biomasses depolymerization, while remaining environmentally friendly. This study aimed to induce xylanase production by Ceratocystis fimbriata using bar- ley, corn cob, and wheat bran as substrates. Additionally, the study evaluated the supplementation of a commercial cellulase cocktail with the partially purified fungal xylanase. The biomass substrates exhibited the highest xylanolytic activity after 8 days of cultivation, with barley yielding 21.20 U/mg. After partial purification through ion exchange chromatography, the xylanase produced in barley demonstrated activity of 67.34 U/mg, resulting in a purification factor of 3.2 and a yield of 56.9 %. The xylanase displayed optimal activity in the pH range of 2.0 to 8.0, retaining more than 50 % of its relative activity. Moreover, the enzyme displayed an optimal temperature of 55 °C and retained over 50 % of its activity after 72 hours at 50 °C. The sup- plemented Multifect® CL cocktail retained xylanase activity above 50 % for 72 hours, unlike the non-supplemented one. These findings unveiled the thermostability of C. fimbriata xylanase. Finally, the supplementation resulted in hydrolysis enhancement of pretreated sugarcane bagasse, leading to an increase of over 40 and 80 % in glucose and xylose production, respectively.

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