Production of xylanase by a new strain of Thermoascus aurantiacus: obtainment of enzymatic extract with reduced cellulolytic activity for application in pulp and paper industries

Abstract

ABSTRACT:Xylanases are useful in several industrial segments, including pulp and paper bleaching, animal feed, and bread-making processes. However, the industrial use of these enzymes is closely related to its production cost and its catalytic properties. The process of solid state fermentation enables the use of agro-industrial residues as substrates for microbial cultivation and enzymes production, reducing costs. In the present study, different cultivation parameters were evaluated for the xylanase production by the thermophilic fungus Thermoascus aurantiacus, by solid state fermentation, using agro-industrial residues as substrates. High production of xylanase (1701.9 U g -1 of dry substrate) was obtained using wheat bran containing 65% of initial moisture, at 120 h of cultivation, and 45°C. The xylanase showed optimal activity at pH 5.0 and 75°C; its stability was maintained at pH 3.0-11.0. The enzyme retained its catalytic potential after 1 h, at 75°C. The enzymatic extract produced under optimized conditions showed reduced activities of endoglucanase and FPase. Our results, including the xylanase production by T. aurantiacus in low-cost cultivation medium, high structural stability of the enzyme, and reduced cellulolytic activity, encourage the application of this enzymatic extract in pulp and paper bleaching processes.

Catalytic properties of cellulases and hemicellulases produced by Lichtheimia ramosa: Potential for sugarcane bagasse saccharification

“…Several studies have emphasized the advantages of using wheat bran as a solid-state substrate for filamentous fungi cultivation for the production of cellulases and hemicellulases (Costa et al, 2016;Delabona et al, 2013;Gowdhaman et al, 2014;Kilikian et al, 2014;Santos et al, 2016).…”

“…Cellulases and hemicellulases were produced by fungus cultivation in 250 mL Erlenmeyer flasks containing 5 g of agroindustrial by-products (wheat bran, soy bran, corn cob, corn straw, rice husk, and sugarcane bagasse), and the initial moisture was adjusted to 75% with the nutrient solution (described in item 2.2). The enzymes were extracted from the fermented products 96 h after fermentation at 28°C (Costa et al, 2016;Santos et al, 2016). The ideal substrate for the production of the enzymes was used in the subsequent steps to evaluate the effects of moisture content (50-80%), temperature (20-45°C), and time of cultivation (24-144 h).…”

“…However, the high cost of producing these biocatalysts remains a problem for the conversion of lignocellulosic material via enzymatic hydrolysis and is a limitation to the production of ethanol from vegetable biomass (Bussamra et al, 2015). In this sense, recent studies have sought to reduce the final cost of these enzymes by prospecting strains with a potential to produce high concentrations of enzymes by low-cost methods (Costa et al, 2016;Delabona et al, 2013;Lan et al, 2013;Santos et al, 2016).…”

Catalytic Properties of Amylolytic Enzymes Produced by Gongronella butleri Using Agroindustrial Residues on Solid-State Fermentation

“…Previous studies have confirmed wheat bran as an excellent substrate for the cultivation of filamentous fungi to produce several enzymes, such as amylases, β -glucosidases, xylanases, and cellulases [ 1 , 4 , 10 , 18 ]. Thus, wheat bran was selected as the substrate for subsequent assays.…”

“…Availability of water in the culture medium favors biological functions and structurally stabilizes biomolecules. However, reduced water activity can affect the process of germination, sporulation, and formation of metabolites, which compromises enzymatic production [ 1 , 18 ].…”