Production of xylanolytic enzymes during growth on pulverized grass by Aspergillus ochraceus-42 |
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Authors: | Amitabha Das Geeta Nanda |
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Institution: | Department of Microbiology, Bose Institute, Calcutta, India |
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Abstract: | Xylanase and β-xylosidase with activity of 6.46 U mg-1 and 0.500 U mg-1, respectively, were produced extracellularly by Aspergillus ochraceus during growth on pulverized grass in liquid state fermentation, compared to 9.3 U mg-1 and 0.74 U mg-1 when pure xylan was used. The culture filtrate was devoid of any cellulase activity. Xylanolytic enzymes were produced optimally in 144 h of incubation on 1% pulverized grass, pH 6.5. About 8.43% (w/w) sugars were liberated from alkali-treated grass in 6 h by the synergistic effect of xylanolytic enzymes. The half-lives for xylanase and β-xylosidase at 50°C were 210 min and 300 min, respectively, and half-life increased with the increase in protein concentration. Both mono- and divalent cations, especially K+ and Zn2+, exhibited a profound effect on the rate of enzyme saccharification. |
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