β-Glucosidase production by a novel marine fungus <i>Cladosporium pseudochalastosporoides</i> : Purification and characterization

This study explores cellulase production from marine microorganisms as a sustainable solution for biofuel generation, utilizing their unique enzymatic adaptations for degrading cellulosic biomass under harsh conditions. A novel marine fungal strain, Cladosporium pseudochalastosporoides , was isolated from a mangrove area in Taiwan and identified as a potent producer of cellulolytic enzymes. Key production parameters, including pH, incubation time, temperature, substrate ratio, and nitrogen source, were optimized. Maximum β-glucosidase (BGL) activity was achieved at pH 7, 25 °C, after 7 days, with a wheat bran-to-Avicel ratio of 1:2.3 and 3% (w/v) corn steep liquor. The enzyme was purified using acetone precipitation and DEAE-Sephadex A-25 ion exchange chromatography, achieving a 17-fold purification and specific activity of 6.8 U/mg. The purified BGL, with a molecular weight of ∼90 kDa, showed optimal activity at pH 6.0 and 50 °C. Activity was retained for 40 min before declining, likely due to its purified state. Enhanced activity was observed with 5 mM concentrations of Fe²⁺, Mg²⁺, Cu²⁺, and Mn²⁺ ions, highlighting its industrial potential. This is the first report characterizing BGL from C. pseudochalastosporoides , underscoring its potential for efficient biomass degradation and biofuel production. Highlights A novel cellulase-producing fungus Cladosporium pseudochalastosporoides was isolated from Taiwan mangroves. BGL produced was moderate glucose tolerant and was purified and characterized. BGL was optimally active at pH 6, 50 °C, and was enhanced by Fe²⁺, Mg²⁺, Cu²⁺, Mn²⁺ ions. C. pseudochalastosporoides was a robust fungus producing cellulase.