Selection of thermophilic and thermotolerant fungi for the production of cellulases and xylanases under solid-state fermentation

Abstract

Twenty-seven thermophilic and thermotolerant fungal strains were isolated from soil, decaying organic matter and sugarcane piles based on their ability to grow at 45°C on medium containing corn straw and cardboard as carbon sources. These fungi were identified in the genera Aspergillus, Thermomyces, Myceliophthora, Thermomucor and Candida. The majority of the isolated strains produced xylanase and cellulases under solid state fermentation (SSF). The highest cellulase and xylanase productions were obtained by the cultivation of the strains identified as Aspergillus fumigatus M.7.1 and Myceliophthora thermophila M.7.7. The enzymes from these strains exhibited maximum activity at pH 5.0 and at 60 and 70ºC. The endo-glucanase from A. fumigatus was stable from 40°C to 65°C and both endo-glucanase and xylanase from M. thermophila were stable in this temperature range when in absence of substrate. The enzymes were stable from pH 4.0 to 9.0.

Substract and temperature effect on xylanase production by aspergillus fumigatus using low cost agricultural wastes

“…Moreover, 80% of the optimum activity was obtained at pH range of 3.5 to 5.0. Other studies reported an acid optimum pH for xylanase from A. fumigatus strains (MORETTI et al, 2012;SOUZA et al, 2012). Optimum temperature was observed at 60 °C, suggesting that this xylanase can be a thermophilic enzyme which can be useful for many biotechnological processes which operate at high temperatures ( Figure 3B).…”

“…The fungus Aspergillus fumigatus is a widespread species commonly found in agricultural residues with numerous biotechnological applications. Previous studies reported its ability to produce secondary metabolites with antimicrobial activity (ARAÇARI et al, 2002), and many enzymes such as proteases, cellulases and xylanases (OYELEKE et al 2010;MORETTI et al, 2012;SOUZA et al, 2012). In this work, a thermotolerant A. fumigatus SCB4 strain isolated from sugarcane bagasse piles from Brazilian Cerrado was evaluated for the production of extracellular xylanase.…”

“…Filamentous fungi are known to be good producers of extracellular xylanases by solid-state fermentation (SSF) using lignocellulosic agricultural by-products as components of microbial growth media, with several economic advantages: low water output, cheap substrates, low risk of contamination and low operating costs (MORETTI et al, 2012;TERRASAN;CARMONA, 2015). Among these residues, sugarcane bagasse is one of the most important in Brazil and is composed by approximately 50% cellulose, 25% hemicellulose and 20% lignin (PANDEY et al, 2000).…”

“…In industrial processes, thermotolerant xylanases are desirable since high temperatures are required to increase solubility of substrates, to reduce viscosity and to reduce the risk of contamination (MORETTI et al, 2012). As a result, the search for thermophilic microorganisms with potential for the synthesis of such enzymes has increased considerably in the last years, mainly 916 Substract and temperature… GOMES,A.…”

“…As a result, the search for thermophilic microorganisms with potential for the synthesis of such enzymes has increased considerably in the last years, mainly 916 Substract and temperature… GOMES,A. F. S. et al filamentous fungi, which have been the most chiefly employed (JOSHI; KHARE, 2012;MORETTI et al, 2012). The fungus Aspergillus fumigatus is a widespread species commonly found in agricultural residues with numerous biotechnological applications.…”