Researchers cultivate an archaeon that breaks down oil all by itself

Microbes are capable of converting oil into natural gas, i.e., methane. It was earlier perceived that this conversion was possible only through the cooperation of various organisms.

In an oil field like this, Gunter Wegener and his colleagues found the microorganisms that now also live in their laboratory. Genetic information shows that they are widespread and even live in the deep sea. Image Credit: © Yoshi Canopus/CC-BY-SA-4.0

In 2019, Rafael Laso-Pérez and Gunter Wegener from the Max Planck Institute for Marine Microbiology proposed that a special archaeon can make this possible all by itself, as shown by the genome analyses. Recently the researchers associated with a group of researchers from China and succeeded in growing this “miracle microbe” in the lab.

This facilitated the researchers to elaborate on how exactly the microorganisms achieve the transformation. They also identified that it prefers to consume bulky chunks of food.

Underground oil deposits both on land and in the sea are harbor many microbes that utilize the oil as an energy source and food, converting it into methane. To date, it was believed that this conversion was possible only in complicated teamwork between numerous organisms—some bacteria and usually two archaeal partners.

However, scientists have recently cultured an archaeon known as Methanoliparia from a settling tank of an oil production facility that regulates this complex reaction alone.

Enzymes just in case

This “miracle microbe” breaks down the oil into carbon dioxide (CO₂) and methane (CH₄).

Methanoliparia is a kind of hybrid creature that combines the properties of an oil degrader with those of a methanogen, i.e., a methane producer.”

Gunter Wegener, Study Author, Max Planck Institute for Marine Microbiology

Gunter Wegener is also associated with the MARUM—Center for Marine Environmental Sciences at the University of Bremen.

As the scientists have succeeded in culturing these microbes in the lab, they could investigate the underlying mechanisms in detail. They identified that its genetic make-up provides Methanoliparia with unique capabilities.

In its genes, it carries the blueprints for enzymes that can activate and decompose various hydrocarbons. In addition, it also has the complete gear kit of a methane producer.”

Gunter Wegener, Study Author, Max Planck Institute for Marine Microbiology

New pathway of methanogenesis

The scientists in the lab cultures provided the microorganisms with different kinds of food and employed various techniques to keep a watch on how Methanoliparia deals with it. It was surprising to visualize how the archaeon activated all the various hydrocarbons with the same enzyme.

So far, we have only cultivated archaea that live on short-chain hydrocarbons such as ethane or butane. Methanoliparia, on the other hand, prefers heavy oil with its long-chain compounds.”

Rafael Laso-Pérez, Study Co-Author, National Center for Biotechnology

Rafael Laso-Pérez further adds, “Methanogenic microbes that use long-chain hydrocarbons directly – we didn't know these existed until now. Even complicated hydrocarbons with ring-like or aromatic structures are not too bulky for Methanoliparia, at least if they are bound to at least one longer carbon chain. This means that besides our other exciting results we have also found a previously completely unknown pathway of methanogenesis.”

Detectable from the oil tank to the deep sea

The cultured Methanoliparia cells originated from one of China’s biggest oil fields, the Shengli oil field. But genetic analyses reveal that these microorganisms are distributed globally, even down to the deep sea.

Wegener also adds, “Our results hold an entirely new understanding of oil exploitation in subsurface oil reservoirs. Both the wide distribution of these organisms and the potential industrial applications make this an exciting field of research in the coming years.”