Biodegradation inducers to enhance wheat straw pretreatment by Gloeophyllum trabeum to second-generation ethanol...

The native state of lignocellulosic biomass is highly resistant to enzymatic hydrolysis and the fermentation process of biofuel production. Brown-rot fungi use an extracellular Fenton system to degrade lignocellulosic biomass in the initial stages of decay. In this work, the combined effects of Mn²⁺, Fe²⁺, and NO₃^- inducers were evaluated based on the activities of hydrolytic enzymes and Fe³⁺ reduction as well as the catechol-type compound production during wheat straw pretreatment by the brown-rot fungus Gloeophyllum trabeum. Weight loss and chemical changes were evaluated to establish the culture conditions for stimulating wheat straw degradation using a central composite design. The results showed that weight loss and the Fe³⁺-reducing activity were promoted at the highest concentrations of Fe²⁺. A positive effect on catechol compound production by the addition of Mn²⁺ and NO₃^- was observed. Cellulase activity was increased at the highest concentration of NO₃^-. The multiple optimizations of G. trabeum culture conditions in wheat straw resulted in 11.3% weight loss and 0.47 total crystallinity index at 0.24 M NO₃^-, 0.95 mM Fe²⁺, and 0.85 mM Mn²⁺ after 40 days. The wheat straw pretreatment by G. trabeum for 10 days increased glucose recovery. The results indicated that the wheat straw pretreatment using G. trabeum with biodegradation inducers could be a complementary step to physicochemical pretreatment of lignocellulosic biomass for production of second-generation ethanol.