Purification and characterization of a novel endo-β-1,4-glucanase from the thermoacidophilic Aspergillus terreus

Abstract

An endo-beta-1,4-glucanase from a thermoacidophilic fungus, Aspergillus terreus M11, was purified 18-fold with 14% yield and a specific activity of 67 U mg(-1) protein. The optimal pH was 2 and the cellulase was stable from pH 2 to 5. The cellulase had a temperature optimum of 60 degrees C measured over 30 min and retained more than 60% of its activity after heating at 70 degrees C for 1 h. The molecular mass of the cellulase was about 25 kDa. Its activity was inhibited by 77% by Hg(2+) (2 mM) and by 59% by Cu(2+) (2 mM).

Optimization and characterization of cold-active endoglucanase produced by Aspergillus terreus strain AKM-F3 grown on sugarcane bagasse

“…EDTA had much less of an effect on the activity. The CAEG was found to be resistant to SDS and Triton X-100, having a relative activity above 80%, which was found to be high when compared with other reports (Gao et al, 2008;Elshafei et al, 2009). 3.4.6.…”

“…The optimum pH for the stability of EG from A. terreus strain AKM-F3 was found to be pH 7.0 (100% relative EG activity = 26.17 U/mg) and almost 90% of relative activity was shown at pH 5.0-8.0 ( Figure 13). The EG from A. terreus M11 was stable at pH 2.0-5.0 (Gao et al, 2008), while the EG from A. terreus strain AN 1 was stable at pH 3.0-5.0 (Nazir et al, 2009). Acids or bases alter a protein's 3D structure because the H + and OH -compete with the hydrogen and ionic bonds in an enzyme, resulting in denaturation (Tortora et al, 2004).…”

“…All of the other ions showed relative EG activity within the range of 67.84%-88.20%. The EG activity of A. terreus M11 was inhibited by 77% and 59% in the presence of 2 mM Hg 2+ and 2 mM Cu 2+ , respectively (Gao et al, 2008 (Garg and Neelakantan, 1982). The ions bind to the enzyme and change the conformation of the protein to counter greater stability for the enzyme (Rahman et al, 2005).…”

An Overview on Fungal Cellulases with an Industrial Perspective

“…For instance, the cellulase produced by A. niger IFO31125 showed an optimum temperature of around 70°C at pH 6 with stability for 2 h [71]. The pH and the temperature optima of the cellulase produced by A. terreus M11 was found as 2 and 60°C, respectively; and 60% of the initial activity was maintained for 1 h at 70°C [72]. Two endoglucanases, RCE1 and RCE2 produced by Rhizopus oryzae showed 55°C as the optimum temperature for both the enzymes with different pH optima, i.e., 5 and 6, respectively [73].…”

“…Riou et al [74] investigated the effect of different metal ions and detergents on cellulase produced by A. oryzae, and found that Ag + , Hg 2+ Fe 3+ , SDS, diethylpyrocarbonate, castanospermine, dithiothreitol were slightly or completely inhibited the cellulase activity; whereas Mn 2+ enhanced the activity. Similarly, the activity of cellulase produced by A. terreus M11 was increased in the presence of Mn 2+ ; but the presence of Hg 2+ , Cu 2+ , Pb 2+ and detergents slightly decreased or completely abolished the activity of cellulase [72]. Yang et al [80] demonstrated that the cellulase produced by Paecilomyces thermophila was strongly inhibited by Hg 2+ ; while the activity was highly enhanced in the presence Zn 2+ .…”