Bacteria that consume CO would be a great ally in the face of climate change. Source: image edited by @emiliomoron, original from pixabay.com.
As we know, carbon monoxide is a poisonous gas for the human being, it is capable of killing a person who inhales it in a matter of minutes, however, there are some microorganisms that are not only capable of tolerating it but also of using its reducing power for their metabolic functions. Such is the case of the bacterium Clostridium autoethanogenum, this bacterium has the ability to use CO as the only source of carbon and energy to grow, so this organism could become a biotechnological tool to be used in the bioremediation of CO-rich waste gases, and produce biofuels. Under this approach, scientists from the Max Planck Institute for Marine Microbiology in Bremen have made an interesting discovery, the results of which were shown in the journal Biochimica et Biophysica Acta (BBA) – Bioenergetics.
In many industries, we see how waste gases made up mainly of carbon monoxide and carbon dioxide, gases that we know are responsible for the greenhouse effect, are vented into the atmosphere on a daily basis from their chimneys. But this could soon change thanks to the power of these CO-eating bacteria. In the work presented, the scientists managed to characterize structurally and biochemically the key enzyme of CO conversion metabolism: CO-Dehydrogenase/Acetyl-CoA synthase (CODH/ACS). This acetogenic-type bacteria uses the Wood-Ljungdahl pathway for carbon fixation and energy conservation, a primary metabolism responsible for up to 20% of global CO2 fixation.
According to the researchers, in the Clostridium autoethanogenum the enzyme CODH/ACS has not only one but several openings. In this way it is able to collect as much CO as possible and lead it to a whole system of tunnels that ensures a high flow of carbon monoxide conversion towards energy conservation and carbon monoxide assimilation, acting as a cellular energy plant. And at the end of the process, acetate and ethanol are generated, which can be used to produce biofuels.
Bacteria would act as biocatalysts in the conversion of CO into higher value products. Source: image designed by @emiliomoron, contains public domain image.
Without a doubt, the study of this complex behavior, drives to investigate if there are other systems that can adapt to this application, and by understanding how evolution shaped these enzymes to adjust to such extreme physiological needs, will allow to develop in the future a series of biocatalysts that serve as a tool to fight climate change. That although it is difficult to reverse, it could be possible to produce fuels with a minimum contribution of CO and CO2 to the environment, since biofuels produced by bacteria that previously consumed these gases would be burned.
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