"Nature": Chinese scientists discover a new way for archaea to produce methane

▎Editor of WuXi AppTec content team Methane is a powerful greenhouse gas, but at the same time, this gas is also an important type of renewable energy
.

As early as 1999, German scientists first confirmed the biological process of methane production from the degradation of petroleum hydrocarbons
.

Ten years later, Canadian scientists reported that the degradation of petroleum hydrocarbons in oil reservoirs to produce methane is also a common biological process: microorganisms can "eat" petroleum hydrocarbons and convert this hydrocarbon organic matter into methane, but this conversion process is very slow.
It usually takes 1-3 years
.

The entire conversion process is very complicated and slow, involving two distinct steps, the degradation of organic matter and the synthesis of methane
.

In the past, people have always believed that this process requires at least two different types of microorganisms, which can be realized through close cooperation and mutual metabolism.
They are bacteria that degrade petroleum hydrocarbons and archaea that produce methane
.

▲Green is the latest research.
The methanogen-producing archaea grown in the laboratory (picture source: reference [1]) is today.
A study published in Nature broke this traditional perception
.

The study discovered for the first time a new type of methanogenic archaea that can independently oxidize long-chain alkyl hydrocarbons, and revealed a new way for archaea to produce methane
.

Methanogenic archaea are the earliest type of prokaryotic microorganisms from the origin of life on earth, and they are also the main contributors to global atmospheric methane emissions
.

Together with bacteria, they degrade organic matter and produce methane (that is, biogas fermentation) in an oxygen-deficient environment
.

According to existing research, this archaea can only produce methane through four pathways: acetic acid fermentation, carbon dioxide reduction, methyl splitting, and oxygen methyl conversion
.

In the latest research of "Nature", scientists from the Energy Microbiological Innovation Team of the Biogas Science Institute of the Ministry of Agriculture and Rural Affairs cooperated with Shenzhen University, the Max Planck Institute of Marine Microbiology in Germany, and the Sinopec Key Laboratory of Microbial Oil Extraction.
The fifth way that archaea produce methane
.

The research team collected and cultivated a fast-growing methanogenic culture from Shandong Shengli Oilfield
.

They provided archaea with a variety of different alkyl compounds as food, and then observed how they use these hydrocarbons
.

▲Methane-producing archaea cultivated in the laboratory (photo source: researcher Cheng Lei) Among them, a new type of methanogenic archaea (Ca.
Methanoliparum) has attracted the attention of researchers
.

They do not need the assistance of other bacteria, directly initiate the degradation of hydrocarbons through alkyl-Coenzyme M reductase, and enter the metabolic process of methanogenesis through β-oxidation and WL pathways
.

Unlike sulfate-reducing archaea that feed on short-chain alkanes (such as ethane and butane), new methanogenic archaea are difficult to use short-chain alkanes, but can efficiently degrade long-chain alkanes and contain longer alkyl groups.
Side chain cyclohexane and alkylbenzene
.

Therefore, researchers refer to this new type of archaea as alkyl-trophic methanogenic archaea
.

▲The metabolic pathway of Ca.
Methanoliparum (picture source: Reference [1]) So far, this research has not only expanded people's understanding of the carbon metabolism function of methanogenic archaea, but also has a series of practical application potentials: perfecting carbon Cyclic biogeochemical processes have laid a scientific foundation for the biogasification of residual crude oil from depleted oil reservoirs and the development of green and sustainable low-carbon technologies
.

The first authors of the paper are Zhou Zhuo, Zhang Cuijing, Liu Pengfei and Fu Lin; Researcher Cheng Lei from the Institute of Biogas Science, Professor Li Meng from Shenzhen University, and Dr.
Gunter Wegener from the Max Planck Institute for Marine Microbiology in Germany are the co-corresponding authors of the paper
.

Reference materials: [1] Zhou, Z.
, Zhang, Cj.
, Liu, Pf.
et al.
Non-syntrophic methanogenic hydrocarbon degradation by an archaeal species.
Nature (2021).
https://doi.
org/10.
1038/s41586 -021-04235-2[2] From the oilfield to the lab: How a special microbe turns oil into gases.
Retrieved Dec 22, 2021 from https://