Enhancing Sugar Production from Obeche (Triplochiton scleroxylon K. Schum.) Sawdust by Synergistic Action of Gloeophyllum sepiarium and Aspergillus niger

Abstract

The study aimed to enhance sugar production in Obeche sawdust by the brown-rot Gloeophyllum sepiarium through elimination of the bottleneck caused by cellobiose product feedback inhibition. The study was designed to use Aspergillus niger to produce supplementary β-glucosidase to relieve inhibition of cellobiose-producing cellulase. The study took place in the Microbiology Laboratory, Delta State University, Abraka, between October 2024 and March 2026. Gloeophyllum sepiarium (8) and Aspergillus niger (8) were isolated from deteriorating structural timber and identified by microscopy, cultural characteristics (potato dextrose/malt extract agar), and basidiocarp characteristics. The cellulolytic index (CI) of G. sepiarium isolates was determined using carboxymethyl cellulose (CMC), and the strain with the highest CI was selected for wood degradation and sugar production determinations using the dinitrosalicylic acid method. CMCase activity in the wood during degradation was determined. The hydrolytic index (HI) of A. niger isolates was determined on cellobiose agar, and the isolate with the highest HI was selected. The identities of both selected strains were confirmed by molecular methods. The influence of pH, nitrogen sources, and temperature on CI and HI was determined. CI and HI ranged from 1.8-3.2 and 1.4-4.2 for G. sepiarium and A. niger, respectively. Comparative analyses indicated that the optimum conditions for CI and HI were pH 6, beef extract, and 35 oC (F=5.92-85.93, P=0.016-0.000). The selected Gloeophyllum sepiarium strain had the highest CI and caused greater sawdust weight loss (30.5-36.9 vs 27.7-32.4%) under optimum conditions. Sugar produced by the strain peaked at 42.4 mg/g after 3 weeks, declined to 20.2 mg/g, and then rose to 31.4 mg/g by the sixth week. CMCase activity in the wood followed the same trend. Combination with A. niger produced markedly higher sugar concentrations (64.7 vs 42.4 mg/g) over 6 weeks without a declining trend. Introduction of A. niger 2 weeks into degradation by G. sepiarium yielded 62.4 mg/g sugar in 20 days. This synergism may be useful in biotechnological applications involving renewable resources.