Screening and Identifying Cow Dung Bacteria for Biogas Production

Abstract

The drive to reduce fossil fuel usage has inspired the investigation of cow dung bacteria in producing biogas. Bacteria were assayed by standard microbiological methods from randomly collected cow dung from a Kwara State, Nigeria ranch. The isolates were grown on thioglycolate agar plates, colonies characterized by biochemical colony morphology techniques, and their pure culture incubated at 25°C, 37°C, and 55°C, and pH 3.6, 5.8, 6.5, 8.0, respectively. After, the pure isolates most resilient to wide pH and temperatures were grown in thioglycolate broth cultures and incubated anaerobically at 37°C for 24 hr for biomass and biogas for ten days. The isolates with significant yields were identified using 16S rRNA sequencing. Twenty bacterial species were isolated, of which 70% were gram-positive and 30% gram-negative. Most isolates grew at 3.6 to 8.0 pH, 25°C to 37°C, and only 2% grew at 55°C. Eight bacterial species produced biogas of which 3 exhibited the best yields, peaking at 0.12 ml. These were identified as Bacillus licheniformis (DC7), Providencia rettgeri (DC10) and DC17. Their survival consistency in challenging environmental conditions underscores their suitability for industrial biogas and cow dung as bacteria sources, supporting their applications for scalable biogas technologies, energy security, and organic waste management.