초록
<P><B>Abstract</B></P> <P>Increasing energy demands call for sustainable alternative sources. Solid state fermentation (SSF) of raw oil palm frond leaves (OPFL) as the substrate to produce extracellular cellulases and xylanase by a novel <I>Rhizopus oryzae</I> UC2 (GenBank accession no. MF767597) was optimized. Optimum SSF conditions (30 °C, 40% moisture content, 2.0 × 10<SUP>8</SUP> spores/g inoculum size) yielded the maximum carboxymethyl cellulase (CMCase) (94.68 U/g), filter paperase (FPase) (25.46 U/g), β-glucosidase (145.47 U/g) and xylanase (213.99 U/g) activities, showing a broad pH range of between 6.0 and 12.0. Proteome analysis of crude enzyme cocktail revealed three β-glucosidases, as well as one endo-β-1,4-glucanase, exoglanase and endo-β-1,4-xylanase each. Activities of the enzyme complex were maximal at an acidic pH and temperature that ranged between pH 3.0–5.0 and 50–60 °C, respectively. <I>In situ</I> hydrolysis of OPFL released various concentrations of sugars <I>viz.</I> glucose (26.74 mg/g), xylose (1.44 mg/g), fructose (50.8 mg/g) and cellobiose (58.31 mg/g). Moreover, CMCase, FPase, β-glucosidase and xylanase exhibited half-lives of 5.13, 1.48, 18.81, 9.23 h when incubated at 60 °C, respectively. Thus, the desirable qualities of <I>R. oryzae</I> UC2 seen here supported its prospective biocatalytic role for timely and safe production of digestible carbohydrates from agro-industrial biomass for the subsequent biotransformation into biofuel.</P> <P><B>Highlights</B></P> <P> <UL> <LI> SSF parameters for production of fungal cellulase and xylanase were optimized. </LI> <LI> The first report on fungal β-glucosidase showing the optimum activity at pH 3. </LI> <LI> High hydrolysis efficiency (75.95%) of raw OPFL yielded high reducing sugars. </LI> <LI> OPFL is a prospectively cheap substrate for SSF to produce cellulolytic enzymes. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>