Found a key process for methane gas formation
José Pichel Andrés/DICYT An international group of scientists, with the participation of The Institute of Natural Resources and Agrobiology of Salamanca (IRNASA, CSIC center), has discovered a regulatory key process in certain microorganisms which produce methane, the main ingredient of natural gas. This process is similar to the one that activates photosynthesis in plants and finding it in anaerobic microorganisms is an important change for the evolutionary biology. That is the reason why this work has been published at the prestigious scientific magazine Proceedings of the National Academy of Sciences of the United States of America (PNAS).
The proteins known as thioredoxins regulate photosynthesis in plants and act as a sensor which differentiates light and dark. Now, scientists of two American universities, Virginia Tech and University of California in Berkeley, with IRNASA and other partnerships, have discovered that they are present in a kind of archaea which are methanogens, that is, organisms which produce methane.
Mónica Balsera, IRNASA researcher and author of the article, explains that the importance of this study is “to show, for the first time, that the thioredoxin’s regulatory system works in the archaeas, which had been studied a lot in plants and it also exists in other organisms, from bacteria to human cells”, mentions to DiCYT, since they act as antioxidant molecules, facilitating other proteins reduction.
Practically, the scientists have analyzed Methanocaldococcus jannaschii, a methanogen that inhabits extreme, oxygen free environments, like hydrothermal and volcanic areas. In this archaea, the thioredoxins would repair spoilt proteins through oxidative processes, this way they would be very important doing exactly what they do. That is why the researchers call attention for the fact that “such an important biological process like methane formation finds itself regulated by this system”.
Implications for bioenergy and medicine
This discovery is very important because the methanogens have a key role in many biological processes, the carbon cycle, for example. In this process, the biomass formed by dead plants transforms itself in gas thanks to these oxygen free microorganisms. This principle is allowing the production of methane from agricultural, livestock or industrial residue. That is the reason why, although it is a basic research, it is directly related to natural gas and, consequently, has implications for bioenergy production. On the other hand, methane is a greenhouse effect gas, so everything related to its production is also related to climate change.
Additionally, these microorganisms are present in some animals’ digestive system in order to contribute to digestion. In humans, they are located in the large intestine, so this knowledge applied to medicine could have implications for nutrition.
The microorganisms in which the thioredoxins were found are not so developed and are so old that “you may infer that this mechanism was present in the Earth before the existence of oxygen”, nevertheless more study is necessary to confirm the evolution of this system.
The story of this research began in 2007, when Bob Buchanan, professor of University of California in Berkeley, and Mónica Balsera worked together in Germany. “We began studying evolutionary aspects of thioredoxins and, through bioinformatics analysis, we verified that some components thought to be plant exclusive could also be found in other photosynthetic organisms, among them, the archaeas”, states the expert. The University of Kiel, in Germany, has also participated of the research, studying the microorganisms’ physiology.
Past the publication of this work at PNAS, IRNASA is trying to characterize biochemically and structurally each component of the thioredoxins system in cooperation with other research groups from Salamanca: the group of Rubén Martínez, of Microbiology and Genetics Department of University of Salamanca, and the one of José María de Pereda, of Cancer Research Center.
Dwi Susanti, Joshua H. Wong, William H. Vensel, Usha Loganathan, Rebecca DeSantis, Ruth A. Schmitz, Monica Balsera, Bob B. Buchanan and Biswarup Mukhopadhyay. 'Thioredoxin targets fundamental processes in a methane-producing archaeon, Methanocaldococcus jannaschii'. PNAS, 2014. doi: 10.1073/pnas.1324240111