Production of xylanase and CMCase on solid state fermentation in different residues by Thermoascus aurantiacus miehe

Abstract

The use of waste as raw material is important for government economy and natural balance. The purpose of this work was to study the production of CMCase and xylanase by a Brazilian strain of Thermoascus aurantiacus in solid state fermentation (SSF) using different agricultural residues (wheat bran, sugarcane bagasse, orange bagasse, corncob, green grass, dried grass, sawdust and corn straw) as substrates without enrichment of the medium and characterize the crude enzymes. The study of the extracellular cellulolytic and hemicellulolytic enzymes showed that T. arantiacus is more xylanolytic than cellulolytic. The highest levels of enzymes were produced in corncob, grasses and corn straw. All the enzymes were stable at room temperature by 24 h over a broad pH range (3.0-9.0) and also were stable at 60ºC for 1 h. The optimum pH and temperature for xylanase and CMCase were 5.0-5.5 and 5.0 and 75ºC, respectively. The microorganism grew quickly in stationary, simple and low cost medium. The secreted extracellular enzymes presented properties that match with those frequently required in industrial environment.

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

“…The moisture present in the solid state fermentation should be sufficient for microorganism development without compromising substrate porosity. A reduced moisture content impairs the fungal accessibility of the medium nutrients, resulting in decreased microbial metabolic activity; in contrast, high concentrations of water favor bacterial contamination and reduce solid matrix porosity, compromising oxygen diffusion and metabolic heat dissipation (DA-SILVA et al, 2005;SADAF and KHARE, 2014). This supports the profile of enzyme production observed in this study ( Figure 1C).…”

“…Thus, the T. aurantiacus strain recently isolated from the region of Dourados-MS has considerable potential for the production of xylanase in low-cost culture media (agro-industrial residues). Previous studies have confirmed the potential to produce xylanase by different strains of the same species isolated from other regions (KALOGERIS et al, 1998;DA-SILVA et al, 2005;BRIENZO et al, 2012).…”

“…Enzymatic extracts used for bleaching of pulp require high concentrations of xylanase, but should have reduced cellulolytic activity so as not to decrease the quality of the pulp (DA-SILVA et al, 2005). This necessary characteristic limits the ability to obtain xylanase by microbial cultivation on complex substrates, such as agro-industrial residues, that are capable of inducing the production of several enzymes, particularly cellulases (BRIENZO et al, 2012).…”

“…Previous studies reported the fungus T. aurantiacus as one of the largest producers of cellulases and hemicellulases, mainly when grown in wheat derivatives (PARRY et al, 2001;KALOGERIS et al, 2003;DA-SILVA et al, 2005), preventing the application of the enzymatic extract in biopulping processes. However, the T. aurantiacus strain evaluated in the present study showed low potential for the production of cellulases (Table 2).…”

“…Previous studies have described different strains of the filamentous fungi Thermoascus aurantiacus as excellent producers of xylanases and cellulases, particularly when grown in agroindustrial residues (KALOGERIS et al, 2003;DA-SILVA et al, 2005), precluding the application of these enzymatic extracts in cellulose pulp bleaching processes due to the high concentration of cellulolytic enzymes. Recently, our research group isolated a new strain of T. aurantiacus with considerable potential for the production of xylanase and reduced cellulolytic activity.…”