Petroleum microbiology is an interdisciplinary area involving microbiologists, biochemists, chemists, chemical engineers, physicists and geologists. A wide range of studies have dealt with processes like biotransformation, biodegradation and bioremediation of petroleum hydrocarbons. Petroleum is a complex mixture of hydrocarbons and other organic compounds, including some organo metallo constituents, most notably complexing vanadium and nickel. Petroleum recovered from different reservoirs varies widely in compositional and physical properties. Long recognized as substrates supporting microbial growth, these hydrocarbons are both a target and a product of microbial metabolism. Practically all geologists agree that petroleum has an organic marine sedimentary origin, but the mode of its formation is not known. Bacterial activity has undoubtedly been involved in petroleum genesis, but the extent to which bacteria have contributed to the formation of petroleum is debatable. Attempts to demonstrate hydrocarbon formation by bacteria under highly artificial conditions have yielded only small amounts of paraffinic hydrocarbons other than methane and practically none of the other myriad compounds present in petroleum. The conservative viewpoint is that bacterial action is limited to producing reduced organic matter more closely resembling petroleum than the original material and that the final stages of petroleum genesis are physicochemical.
