Isolation and Molecular Characterization of Methanogenic Bacteria Consortium involved in Biogas Production from Fruit and Vegetable Wastes from Selected Markets in Kaduna, Nigeria

The objective of this paper was to isolate and molecularly characterize methanogenic bacteria consortium involved in biogas production from fruit and vegetable wastes from selected markets in Kaduna, Nigeria using conventional microbiological methods like Enrichment culture, Gram staining, biochemical tests, colony morphology analysis, selective medium, and motility testing techniques were used for separating and characterizing both Gram-positive and Gram-negative bacteria successfully isolated and identified, including species such as Bacillus spp, Clostridium spp, Pseudomonas spp, Bordetella spp, Lysinibacillus spp, Methanobacterium spp, and Methanobrevibacter spp. Molecular analysis using 16S rRNA sequencing revealed that Methanobacterium formicicum, isolated from Digester C, showed 98% genetic similarity with known strains, supporting its role in biogas production. The anaerobic digesters were loaded with a 1:1 mixture of fruit and vegetable waste combined with cow dung, which acted as an inoculum. This combination enhanced biogas production efficiency by providing a stable substrate for methanogenic activity. Gas analysis revealed that methane () concentrations in Digesters A, B, and C were 72.7%, 73.5%, and 75.2%, respectively. Higher methane concentrations in Digester C resulted in elevated calorific values, reaching 25.15 MJ/m³. The biogas produced was tested for combustion efficiency, with methane content directly correlating to the energy output of the biogas. Digester C, which had the highest methane concentration, also exhibited the greatest energy potential, producing clean-burning biogas suitable for rural energy applications. The study further demonstrated that the combination of fruit and vegetable waste with cow dung accelerates methane production, contributing to more efficient anaerobic digestion. The results provide a foundation for scaling up biogas production using organic waste in developing countries, with potential applications in sustainable waste management, renewable energy generation, and agricultural development.