Enhanced biodegradation of organic waste treated by environmental fungal isolates with higher cellulolytic potential

Lignocellulosic biomass from agricultural waste seems promising feedstock for biofuel production; however, its degradation to fermentable sugars is challenging. Interestingly, fungi have shown substantial potential for the breakdown of lignocellulosic biomass and thus could be employed in lignocellulose-based biorefinery. Aiming at this, the current study was focused on screening the novel cellulolytic fungi from the surrounding environment. The preliminary molecular/morphological screening of 107 samples narrowed the experiment to 5 different fungi, designated: Aspergillus tubingensis AKF2, Aspergillus flavus AKF3, Pyricularia oryzae AKF4, Aspergillus nominus AKF5, and Aspergillus oryzae AKF6. The selected fungi were evaluated for their cellulolytic potential utilizing wheat straw, corn cob, and rice husk. The highest enzyme activity (CMCase: 68.2 U ml −1 ; FPase: 343.3 U ml −1 ; β-Gase: 86.3 U ml −1 ; xylanase: 234.6 U ml −1 ) was observed on the 8th day in the cultures of A. tubingensis AKF2 using wheat straw as compared to corn cob and rice husk. The total reducing sugars released after enzymatic breakdown were also high (437.05 mg g −1 ) in the wheat straw cultures of A. tubingensis AKF2 comprehending the higher cellulolytic activity of this fungus. To further investigate the compositional breakdown, scanning electron microscopy and FTIR were performed. Significant (LSD > 0.05) results were observed in the wheat straw cultures of A. tubingensis AKF2 with 48%, 36%, 39%, and 56% reductions in the cellulose, hemicellulose, lignin, and total mass contents, respectively. The superseding fungus ( A. tubingensis AKF2) identified here could be further optimized for an eco-sustainable biorefinery and may have industrial applications for cellulase production. Graphical abstract