The tiny organisms cling to oil droplets and perform a great feat: As a single organism, they may produce methane from oil by a process called alkane disproportionation. Previously this was only known from symbioses between bacteria and archaea. Scientists from Joint Research Group for Deep-Sea Ecology and Technology of the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) and the Max Planck Institute for Marine Microbiology (MPI), have now found cells of this microbe called Methanoliparia in oil reservoirs worldwide.
Crude oil and gas naturally escape from the seabed in many places known as “seeps”. There, these hydrocarbons move up from source rocks through fractures and sediments towards the surface, where they leak out of the ground and sustain a diversity of densely populated habitats in the dark ocean. A large part of the hydrocarbons, primarily alkanes, is already degraded before it reaches the sediment surface. Even deep down in the sediment, where no oxygen exists, it provides an important energy source for subsurface microorganisms, amongst them some of the so-called archaea.
These archaea were good for many surprises in recent years: Now a study led by scientists from the HGF MPG Joint Research Group for Deep-Sea Ecology and Technology, provides environmental information, genomes and first images of a microbe that has the potential to transform long-chain hydrocarbons to methane. Their results are published in the journal mBio.
Splitting oil into methane and carbon dioxide
This microbe, an archaeon named Methanoliparia, transforms the hydrocarbons by a process called alkane disproportionation: It splits the oil into methane (CH4) and carbon dioxide (CO2). Previously, this transformation was thought to require a complex partnership between two kinds of organisms, archaea and bacteria. Here the scientists present evidence for a different solution. “This is the first time we get to see a microbe that has the potential to degrade oil to methane all by itself”, first-author Rafael Laso-Pérez explains.