Optimizing parameters for production of cell wall hydrolyzing enzymes by Aspergillus eucalypticola AUMC 15402 under submerged and solid-state conditions

Abstract

In this study, a promising fungal isolate has been isolated from sugarcane bagasse, and it has demonstrated a high potential for producing endoglucanase, exoglucanase, and xylanase. The fungus was identified as Aspergillus eucalypticola by using sequencing of the internal transcribed spacer region. At 30 C, sodium nitrate was the best nitrogen source for the maximum activity of endoglucanase (21.0±2.2 U/mg at pH 8.0 after 8 days), exoglucanase (37.8±4.0 U/mg at pH 5.0 after 9 days), and xylanase (42.0±4.0 U/mg at pH 8.0 after 6 days). Endoglucanase and exoglucanase presented their highest activity of 0.362 and 4.25 U/mg, respectively, at pH 8.0 and 45 ºC, while pectinase and xylanase showed their activity maxima of 4.0 and 2.94 U/mg, respectively, at pH 8.0 and 50 ºC. Co2+, Mn2+, SDS, Ca2+, and Ni2+ boosted endoglucanase activity by 138.72, 126.65, 125.24, 110.1, and 104.85 %, respectively. Every material under investigation boosted the activity of exoglucanase, except for Ni2+ and SDS. The increased impact ranged from 101.43% for EDTA to 146.16% for Mn2+. Co2+, Mn2+, SDS, and Fe2+ increased pectinase activity by 123, 118.34, 107.4, and 101.9 %. Mn2+ followed by Co2+, SDS, Fe2+, and Ca2+ improved xylanase activity by 179.4, 167.75, 152.0, 123.35, and 102.0 %, respectively. The strain fermented date palm leaves, rice straw, and sugarcane bagasse under solid state fermentation into endoglucanase (18.0, 16.0, and 9.0 U/g), exoglucanase (20.0±1.64, 25.0±2.0, and 15.0±1.0), pectinase (34.0±2.84, 38.0±2.85, and 38.0±3.0 U/g), and xylanase (25.0±1.8, 28.0±2.0, and 17.0±1.1 U/g), respectively.