Microbes Find A Home In Oily Water Droplets

The latest extreme environment in which microbes have been discovered to exist is within water droplets trapped in a natural asphalt lake, reports a team led by Rainer U. Meckenstock of the German Research Center for Environmental Health (Science 2014, DOI: 10.1126/science.1252215). Anaerobic microbial degradation of hydrocarbons harms the quality of petroleum reservoirs, but scientists had believed that such activity occurred mostly at geological transition zones between layers of water and oil deposits. Studying oil samples obtained from Pitch Lake on the island of Trinidad, Meckenstock and colleagues found bacterial and archaeal communities in droplets containing merely 1 to 3 µL of water. The microbes appear to be degrading linear aliphatic hydrocarbon chains and aromatic compounds to form oxygenated and sulfonated molecules. The high salinity and isotopic profile of the water droplets indicate they originate deep in Earth. The results show that oil degradation can occur even in extremely small pockets of water far from oil-water transition zones.