Solid‐state valorization of raw oil palm leaves by novel fungi Trichoderma asperellumUC1 and Rhizopus oryzaeUC2 for sustainable production of cellulase and xylanase

Abstract

BACKGROUND:The growing demand for cellulases and xylanases in lignocellulosic degradation and reutilization has spurred the need for their improved production at reduced cost. Abundantly available oil palm leaves (OPL) promise an alternative and sustainable substrate for producing such enzymes in the degradation and biotransformation of unwanted lignocellulosic biomass. Both enzymes are key players in the transformation of biomass into other value-added commodities.RESULTS: This study statistically optimized the solid-state fermentation (SSF) of raw OPL by novel fungal strains Trichoderma asperellum UC1 and Rhizopus oryzae UC2, to produce cellulase and xylanase, where raw OPL was pretreated using ultrasonication before the dual enzyme-assisted saccharification process. This experiment aimed to identify the best parameters for the highest activity of CMCase (EC 3.2.1.4), FPase (EC 3.2.1.91) and xylanase (EC 3.2.1.8) of T. asperellum UC1 and of ⊎-glucosidase (EC 3.2.1.21) of R. oryzae UC2 for improved saccharification. Activities of CMCase (126.87 U g −1 ), FPase (85.53 U g −1 ) and xylanase (215.42 U g −1 ) achieved the maximum under optimized SSF conditions (30 °C, 2.0 × 10 7 spores g −1 , 75% moisture content, pH 6). The best ⊎-glucosidase activity (131.76 U g −1 ) was obtained at 32 °C, 2.0 × 10 7 spores g −1 , 50% moisture content, pH 12. OPL saccharification yielded 1240 ± 32 mg g −1 total reducing sugar. Individual enzyme cocktails improved juice clarification (84-88%) and dough rising (1.7-to 2.0-fold).CONCLUSIONS: The optimized SSF of raw OPL successfully afforded the production of effective cellulases and xylanases for saccharification-related reactions.

Optimization of Endoglucanase Synthesis by Trichoderma harzianum via Taguchi Approach

“…Lignocellulolytic biomass waste is commonly used as the readily available substrate or carbon source for fungal fermentation activity. As established by the previous reports, various kinds of biomass waste such as sugarcane bagasse [12], wheat bran [12,13], corn straw [7], groundnut shell [14], and oil palm biomass [8,9,15,16] would result in enzyme production showing different enzymatic activities. The higher cellulose content in oil palm leaves (OPL) (40%) than other biomass such as trunks (34%) and empty fruit bunches (23%) [17] shows its potential to produce cellulolytic and xylanolytic enzymes.…”

“…The higher cellulose content in oil palm leaves (OPL) (40%) than other biomass such as trunks (34%) and empty fruit bunches (23%) [17] shows its potential to produce cellulolytic and xylanolytic enzymes. The feasibility of OPL in the fermentation process was demonstrated by Ezeilo et al [8] in the cellulase synthesis by Trichoderma asperellum. However, the OPL employed in this study has a more accessible particle size, which could boost endoglucanase production in a shorter period.…”

“…Significantly, the metabolic process of fungal growth, related to its activity in substrate degradation, depends on environmental factors. Therefore, researchers have been working on optimizing the fermentation process in synthesizing fungal cellulases [6][7][8][9]. The fermentation process can be manipulated by various parameters, including the fungi species, inoculum size, carbon source, temperature, and humidity.…”

Microbial enzymes for green energy and clean environment

“…[1][2][3][4][5][6][7][8][9][10][11][12] In addition to this various biomass, biopolymers including lignin, cellulose, and municipal-, industrial-, and agricultural-based pollutants were documented to convert into valuable products using enzymatic pathways. [13][14][15][16] The cutting-edge technologies of protein engineering and directed evolution have already minimized the cost of enzymatic transformation processes with higher product yield. Both microbes and their enzymes significantly contribute to parallel ecosystem stability in environmental pollution and clean energy generation.…”