This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A newly identified Arctic Ocean bacterium may have an unusual way of making the building blocks it needs to grow. Using acetone, a common chemical in seawater, the bacteria incorporate carbon dioxide (CO₂) into their metabolisms, allowing them to survive in waters where nutrients and usable organic matter are scarce.
In a study published in Nature Communications, Concordia researchers describe how Porticoccus arcticus survives in the frigid waters of the Beaufort Sea, just north of the Yukon in the Arctic Ocean's Canada Basin. The team found genomic evidence that the bacterial population uses acetone carboxylation, a process that converts acetone and carbon dioxide into compounds that can enter the cell's central metabolic pathways. "This study introduces two new discoveries," says David Walsh, a professor in the Department of Biology and the paper's corresponding author.
"The first is a group of organisms, P. arcticus, that has a unique metabolism that uses organic carbon while at the same time has the capacity to use light as an energy source. We call this process photoheterotrophy. "The second discovery is the way the organism consumes acetone to also consume carbon dioxide out of the atmosphere.
This acetone-mediated inorganic carbon assimilation combines what animals do—eating food, in this case, acetone—with what plants do: fixing CO₂." Acetone is produced by marine organisms, including microscopic algae, and through chemical reactions involving sunlight and dissolved organic matter. Although scientists have identified other ways marine bacteria consume acetone, this study provides evidence of a different pathway in Arctic waters. Genetic analyses suggest that P. arcticus has adapted to life near the ocean surface.
At some locations, it accounted for up to 9% of detected bacteria, making it an important member of the Arctic microbial community. The researchers note that the bacterium's relatively small genome contains the complete set of genes needed for acetone carboxylation, as well as multiple genes for light-sensitive proteins called proteorhodopsins that help cells capture energy from sunlight. Analyses showed that genes involved in both acetone processing and light capture were among the organism's most active.
The researchers say these traits may allow the bacterium to use sunlight for energy while supplementing its carbon supply through acetone metabolism and carbon dioxide assimilation. "The genomic composition of these organisms led us to reconstruct the different types of energy and carbon metabolisms that exist," Walsh says. "That is how we found this very specific set of genes associated with the use of acetone, which was unexpected.
Extract — continue reading at the source.
