Fungal-assisted valorization of raw oil palm leaves for production of cellulase and xylanase in solid state fermentation media

Abstract

Abstract: As yet, the full potential of raw oil palm frond leaves (OPFL) is not fully explored. This study therefore, evaluated OPFL as cheap and sustainable growth substrate for two novel fungi species to produce cellulase and xylanase under solid-state fermentation (SSF). 18S rRNA, phylogeny and BIOLOG® analyses identified the cellulase and xylanase-producing fungal strains as Trichoderma asperellum UC1 and Rhizopus oryzae UC2. In addition to being more robust and fast-growing, strain UC2 demonstrated rapid spore production and exhibited sustained production of cellulase and xylanase as compared to the fungal strain UC1. Maximum endoglucanase, exoglucanase, β-glucosidase and xylanase activity for strain UC1 were recorded as 59.64 U/g, 9.58 U/g, 118.1 U/g and 175.91 U/g, respectively, while UC2 gave the corresponding enzyme activity of 41.62 U/g, 7.65 U/g, 113.07 U/g and 162.68 U/g. It was apparent that strains UC1 and UC2 grew well under SSF of raw OPFL, envisaging the feasibility of this form of oil palm biomass as growth substrate for fungi, yielding satisfactorily high titers of cellulase and xylanase. Noteworthily, the approach adopted by this study offers an alternative avenue to valorizing agriculture biomass, in conjunction to sustainably produce cellulose-acting enzymes to catalyse biofuel and platform chemical productions.