Sulfur-oxidizing bacteria (SOB) are lithoautotrophs; lithos meaning rock or mineral, for their ability to feed on elemental sulfur (S0); autotroph meaning self-feeding, for their ability to produce the complex compounds needed for cell growth - carbohydrates, proteins, fats, nucleic acids - from simple substances - energy from hydrogen sulfide (H2S) and oxygen (O2), and carbon from carbon dioxide (CO2).