Some nitrogen-fixing microorganisms contain an enzyme for the simultaneous production of ammonia and methane
An unexpected source of methane in the environment has been inadvertently discovered.
This animation shows how a nitrogen-fixing microbe, R. palustris can also produce methane using iron-only nitrogenase and how, in a lab culture, the methane can support the growth of a methane-utilizing Methylomonas.
Credit: Harwood lab/UW Medicine
Usage Restrictions: For use only by news organizations in reporting on the work of the Harwood lab
Nitrogen-fixing bacteria are the chief means by which nitrogen gas in the air is changed into a form that plants and animals can use. Roughly 10 percent of these nitrogen-fixing microorganisms contain the genetic code for manufacturing a back-up enzyme, called iron iron-only nitrogenase, to do their job.
Recent research reveals that this enzyme allows these microorganisms to convert nitrogen gas to ammonia and carbon dioxide into methane at the same time. The ammonia is the main product; the methane is only a sideline.
This enzymatic pathway is a previously unknown route for the natural biological production of methane.
The findings are reported Jan. 15 in Nature Microbiology. The senior author is Caroline Harwood, the Gerald and Lyn Grinstein Professor of Microbiology at the University of Washington School of Medicine. The lead author is Yanning Zheng, a postdoctoral student in her lab.
"Methane is potent greenhouse gas. That is why it is important to account for all of its sources," Harwood said.
In addition to being released from fossil fuels, methane also comes from microbial activity. In a single year, microorganisms, including many living in the ocean and decaying swamps, form and consume at least a billion tons of methane.
The archaea, single-cell life forms that tend to like harsh environments, are the main methane generators. To accomplish this, they avail themselves of complex chemical pathways, some of which already have been traced by scientists.
Besides its ecological significance, a better understanding of the various ways microorganisms manufacture methane is medically important. Methane production can play a role in the interactions in microbial communities that inhabit humans and animals. Methane in the gut, for example, is suspected of contributing to some digestive disorders.
However, although iron-only nitrogenase was identified several decades ago, scientists had not yet noticed that it, too, could be used by some microorganisms for methane production.
"It's been a neglected enzyme," Zheng said.
His team is studying an adaptable bacteria that can acquire its energy from a variety of reactions, Rhodopseudomonas palustris. Still, the researchers did not expect that the methane they were seeking would be generated by iron-only nitrogenase in this organism.
"There is now recent evidence that iron-only nitrogenase is active in microbes more often and in more conditions than we had previously thought," Zheng observed.
To make sure this methane-generating pathway was not exclusive to Rhodopseudomonas palustris, they tested for similar abilities in three other nitrogen-fixing bacterial species that have iron-only nitrogenase.
They also examined data that showed that genes for iron-only nitrogenase were detected in a number of physiologically diverse microorganisms that also vary in the conditions under which they survive.
They learned, too, that the Rhodopseudomonas palustris ability to produce even a tiny amount of methane enabled a methane-utilizing bacteria to grow in the same lab culture.
It is likely, according to the researchers, that interactions like these occur in nature and support the activities of methane-oxidizing bacteria. This form of methane production might, for example, help shape microbial community interactions in marine sediments, in the soil, and in microbiomes living in humans and animals.
The researchers' work was supported by a grant from the U.S. Department of Energy. In addition to several other University of Washington researchers, the team included scientists from Utah State University and Montana State University.
Leila Gray | EurekAlert!
Cancer diagnosis: no more needles?
25.05.2018 | Christian-Albrechts-Universität zu Kiel
Less is more? Gene switch for healthy aging found
25.05.2018 | Leibniz-Institut für Alternsforschung - Fritz-Lipmann-Institut e.V. (FLI)
The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.
Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...
A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.
The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...
At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.
At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...
There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?
At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
25.05.2018 | Event News
02.05.2018 | Event News
13.04.2018 | Event News
25.05.2018 | Event News
25.05.2018 | Machine Engineering
25.05.2018 | Life Sciences