How bacteria break down crude oil

An estimated 800 million litres of crude oil spilled into the Gulf of Mexico after the explosion of the Deepwater Horizon drilling platform in April 2010. How does nature manage to recover from such an immense impact? An interdisciplinary team of researchers led by geochemist Prof Dr Heinz Wilkes and microbiologist Prof Dr Ralf Rabus from the Institute of Chemistry and Biology of the Marine Environment (ICBM) at the University of Oldenburg has come a step closer to answering this question. The scientists have discovered how bacteria support the sea in its natural self-cleaning process: The microorganisms have developed a special metabolic pathway. This allows them to utilise a variety of petroleum components as nutrients and convert them in this way. In this way, they make a significant contribution to detoxification. The researchers have published their findings in the scientific journal "Frontiers in Microbiology". Bacteria are true survival artists: they are found in the most extreme places on earth and are particularly good at adapting to environmental conditions. In the course of evolution, for example, some bacteria have found a way to obtain energy from hydrocarbons - even though these are known to be extremely difficult to break down. Hydrocarbons are the main components of crude oil. Humans burn them, for example in a car engine, in order to utilise the energy they contain. Bacteria make it easier for themselves: they simply "eat" these energy-rich components of crude oil. How do the bacteria manage to do this? This was one of the questions that the researchers led by Wilkes and Rabus asked themselves. In order to answer it, they used various bacterial strains from different habitats - from freshwater sediments in Germany and Switzerland, from coastal marine sediments in the USA, from deep-sea sediments in the Gulf of California and from an oil tank in Lower Saxony. What is special about the bacteria analysed: They are anaerobic, i.e. they grow without atmospheric oxygen and extract the energy-rich hydrocarbons from the crude oil. Using microbiological experiments and chemical analyses, the researchers investigated a novel enzyme reaction of these bacteria and discovered its previously undreamt-of far-reaching effect. This enzyme reaction converts an unexpectedly large number of petroleum components. This not only allows the bacteria to grow, but also ensures the detoxification of oil-contaminated marine sediments. The research results contribute to a better assessment and long-term prediction of the self-cleaning powers of nature. In addition, the biochemical reaction principles discovered have potential for innovative biotechnological processes, for example to produce useful products from hydrocarbons instead of simply burning them. The "Organic Geochemistry" and "General and Molecular Microbiology" working groups at the ICBM of the University of Oldenburg, the Max Planck Institute for Marine Microbiology Bremen, the Helmholtz Centre Potsdam German Research Centre for Geosciences and the University of Newcastle were involved in the research.