A new species of bacteria that functions like electrical wiring has recently been discovered on a brackish beach in Oregon. The species was named Candidatus Electrothrix yaqonensis in honor of the Yaquina tribe of Native Americans that once lived in and around Yaquina Bay, where the bacteria were found.
This species is a type of cable bacteria: rod-shaped microbes that are connected at both ends to one another to create a chain and which share an outer membrane, forming filaments several centimeters long. Cable bacteria are found in marine and freshwater sediments and, unusually among bacteria, are electrically conductive. This is due to their special metabolism, in which electrons generated by oxidizing sulfides in their deeper layers are sent to their surface layer, where they are received by oxygen and nitric acid.
The 25 species of cable bacteria known so far have been organized into two genera, Candidatus Electrothrix, which live in saltwater, and Candidatus Electronema, which live in fresh and brackish water. The new species discovered in this study has the genes and metabolic pathways of both the genera but is believed to be a bridge to an earlier branch of the Candidatus Electrothrix lineage, and so was classified as part of that genus.
The recently discovered species may provide new insights into how cable bacteria evolved and how they can function in diverse environments, Cheng Li, a postdoctoral researcher at Oregon State University and coauthor of the research, explained in a statement.
High Electrical Conductivity
Candidatus Electrothrix yaqonensis is distinct from existing cable bacteria in its appearance. Cable bacteria have outer shells that feature ridges, which spread out like mountains. The ridges of the new species are much thicker than those of previously known species, reaching an average thickness of about 228 nanometers, up to three times thicker than what has been seen before. The new species’ ridges are arranged in a spiral-like pattern on the surface of the filament, and their overall shape is more angular than that of other species.
But the most striking difference is that the new species’ filament is surrounded by a thick, transparent sheath. According to the authors of the paper outlining the discovery, this is a structure not previously seen. This sheath does not conduct electricity and is thought to protect the filament from the environment and foreign enemies.