Utilization of sugarcane bagasse waste by Aspergillus welwitchiae SVUAw9 for production, purification, and...

Aspergillus welwitschiae strain SVUAw9 was isolated from sugarcane bagasse and identified by the sequencing of the calmodulin (CaM) gene, was found to exhibit substantial cold-active xylanase activity in this study. Under solid-state fermentation conditions, the strain can utilize a range of agro-industrial residues as substrates to produce cold-active xylanase. After 14 days at pH 7 and 10 °C using ammonium chloride as the nitrogen source, sugarcane bagasse was the most productive substrate, generating 106.93 ± 12.1 U/gram dry substrate (gds), followed by bean straw, corn cob, and date palm leaves which produced 57.82 ± 8.27, 57.75 ± 7.44, and 38.87 ± 6.15 U/gds, respectively. Conversely, the substrate exhibiting the lowest production was rice husk, producing 29.32 ± 4.88 U/gds. Using Trilite MC 08 and Sephacryl S-200 columns, the xylanase was purified 75.87 times, yielding a single band at approximately 71 kDa. At pH 4.0 and 30 °C, the maximum activity of 156.46 ± 12 U/mg was achieved. Co(NO₃)₂, MnSO₄, and NiSO₄ markedly enhanced enzyme activity, resulting in residual activity increases of 152.94 ± 11.54%, 152.94 ± 9.58%, and 134.12 ± ठर 7.66%, respectively, with specific activities of 239.3 ± 18, 239.3 ± 15, and 209.84 ± 12 U/mg. Km and Vmax for the pure xylanase were determined as 0.1 ± 0.005 mg/mL and 144.9 ± 7.14 µmol/min, respectively. The purified xylanase could degrade oat spelt xylan, corn cob xylan, xylan, Birchwood xylan, maize stalk xylan, carboxymethyl cellulose (CMC), beechwood and microcrystalline cellulose (MCC), resulting in activities of 156 ± 12, 108 ± 7, 82 ± 6, 79 ± 5, 62 ± 4, 22 ± 1.5, and 38 ± 3 U/mg, respectively.