Abstract

We have isolated a large number of microfungi from naturally degrading rice straw (“Parali”) over a period of 3 months of incubation in and on the soil using moist chamber and dilution plate methods. On screening of all species for the production of CMCase activity on agar plates, 10 species of microfungi showed good activity. These included Aspergillus niger, A. flavus, A. oryzae, A. fumigatus, Penicillium chrysogenum, P. expansum, Chaetomium globosum, Fusarium oxysporum, F. rosesum and Trichoderma viride. All these 10 species were cultured for the production of cellulase activity under solid-state fermentation conditions. It was found that Aspergillus orzyae, A. flavus, A. fumigatus, Penicillium chrysogenum and Trichoderma viride showed high cellulases activity in terms of CMCase and FPase. Solid-state fermentation (SSF) medium included 5g rice straw in 500mL Erlenmeyer flask that was moistened with nutrient medium containing urea (1g/L), jaggery (5g/L) and yeast powder (2g/L) for the production of enzymes. Flasks were incubated at 28±2 °C for 14 days and the extracellular enzyme was recovered using citrate buffer and activity was measured in IU/mL using dinitros alicyclic (DNS) acid method. The highest cellulases activity of 37IU/mL was found with Penicillium chrysogenum followed by Aspergillus flavus 10.7IU/mL and A. oryzae 7.6IU/mL. It is suggested that micro-fungi may be used to degrade rice straw under field conditions to enhance its natural degradation to avoid the burning of “Parali” to fight with pollution.

Keywords: Decomposition; Rice straw; Cellulases; Solid state fermentation