Gaseous fuel production from fungal lignocellulose degradation

Anaerobic biodegradation of lignocellulose from elephant grass by cellulolytic fungi was carried out at optimum operational conditions: reactor volume of 50 cm³, slurry concentration of 2:5 w/v lignocellulose (g): water (cm³), and degradation temperature of 33 °C. Four cellulolytic fungi and a bacterium, which were harnessed from the air, were isolated in pure form and identified. Two species, Curvularia and Penicillium, were responsible for the biodegradation of lignocellulosic material, to yield biogas. The other two, Fusarium species and Aspergillus niger, including the bacterium, gave no gaseous products. Three gaseous products, namely methane, propane and carbon dioxide, were identified and measured. The rates of formation of these products were found to be first order with respect to the concentration of lignocellulose and the concentration of the microorganism, respectively. The distribution of the gaseous products suggests that the mechanism involves reductive decomposition of the cellulose monomeric unit, by the microorganism, to the gaseous products formed. Major heavier hydrocarbons produced in the degradation were also identified as mainly saturated polycyclic hydrocarbons, probably formed from the reductive degradation of the polyaromatic portions of the lignocellulose.