A group of college students working on a project on bio-gas have found some bacteria in the bio-gas plant. These bacteria can utilize methane as their source of energy and do not need oxygen for their survival. What kind of bacteria could they be?

These organisms are called anaerobic organisms, specifically a group of archaebacteria. These type of organisms do not need oxygen for survival. They are prokaryotes which means no nucleus. Some organism belonging to this group use methane as their source of energy.