Nitrobacter sp. bacteria. Coloured transmission electron micrograph (TEM) of a section through Nitrobacter sp. bacteria. These are chemolithotrophs, bacteria that can derive energy from inorganic compounds, rather than using organic compounds like most living organisms. As the name implies, Nitrobacter sp. bacteria oxidise nitrogen-based compounds for energy, converting nitrites into nitrates. Each cell has a long flagellum, which can be beaten for propulsion. They reproduce by budding. They are found in both marine and fresh water, and soils. Magnification: x6000 at 6x4.5cm size.