The effects of Pleurotus tuber-regium solid-state fermentation on the fermentation and physical characteristics of selected biomass wastes

The fermentation and physical characteristics of biomass wastes (banana pseudo-stem, empty palm bunch, and rice hull) subjected to solid-state fermentation using the king tuber mushroom (Pleurotus tuber-regium) were investigated. Each of the biomass wastes were milled as necessary and composted for seven days and thereafter inoculated with the mushroom spores and fermented anaerobically to achieve mycelia colonization for the periods of 20, 30, and 40 days in triplicates in a completely randomized design. Data on mycelia colonization, color, odor, pH, and temperature changes were recorded every 10 days. Analysis of physical characteristics was performed on fermented and non-fermented biomass wastes. Results showed that Pleurotus tuber-regium colonized empty palm bunch and rice hull by the 20th day of fermentation but failed to colonize banana pseudo-stem. Mycelia colonization was visually observed to be more extensive on the substrate, with pin head development in empty palm bunch and rice hull by the 30th day, but died off by the 40th day. Fermentation temperature significantly decreased (p<0.05) in all substrates, while pH of empty palm bunch and rice hull increased significantly (p<0.05) from slightly acidic (6.16 and 6.82, respectively) to neutral (7.00). Physical characteristics of all biomass wastes revealed a significant decrease (p<0.05) in treated biomass wastes values compared to control values. It was concluded that the 20-day fermentation period using Pleurotus tuber-regium on composted empty palm bunch and rice hull was optimal, based on the observed improvements in their physical characteristics. This makes them potential feedstuffs for ruminants and pseudo-ruminants.