South Asian Journal of Research in Microbiology

The presence of lignin in lignocellulose substrates greatly limits anaerobic digestion for production of biogas. The need for initial pretreatment to sufficiently remove it became inevitable bacterial pretreatment method was used to pretreat rice straw samples for application in biogas production in a batch bioreactor. Bacterial spp isolated from termite gut were identified by 16S rRNA gene sequencing and a lignolytic isolate identified as Morgenelamorganii strain S4L2C (MH745964) was used for biological pretreatment of the substrate. The pretreated rice straw was co-digested with 1:1, 2:1 and 3:1 ratios of cow dung, pig waste and poultry droppings respectively, as amendments. Proximate composition, lignin, cellulose and hemicellulose content of the feedstock were determined by standard methods. Results obtained revealed that lignin concentration reduced from 17.4% to 7.3% after bacteria pretreatment. The 16S RNA gene analysis of bacterial consortium from termite gut indicated the presence of Escherichia coli andMorgenelamorganii strain S4L2C (MH745964), with 100% and 98.6% similarity, respectively. There was a significant difference (P ≤ 0.05) in biogas yield in all Bacteria pretreated rice straw (BPRS) amended with animal manure compared to untreated rice straw (URS) alone. Bacterial pretreated rice straw (BPRS/CD) 1:1 ratio of rice straw to cow dung showed the highest yield of biogas followed by bacteria pretreated Rice Straw codigested with poultry dropping (BPRS/PD) 2:1 with a cumulative biogas yield of 27.05dm³ and 22.47dm³ respectively. Composition of components gases in biogas produced by rice straw/ cow dung 1:1 which produced highest volume of biogas in this study, were CO 1.15%, CO₂ 33.56% and CH₄ 64.96%. Findings from this study have shown that biological pretreatment of lignocellulosic waste (Rice Straw) using Morgenelamorganii strain S4L2C (MH745964) enhanced biogas production.