A novel discovery in the muddy intertidal zones of the Oregon coast has unveiled a new species of bacterium with the remarkable ability to conduct electricity like a wire.
Dubbed Ca. Electrothrix yaqonensis in a respectful nod to the Yaqo’n people, the First Nations community indigenous to the discovery location, this microbe offers fascinating insights into the evolution and potential applications of bioelectric organisms.
This newly identified bacterium belongs to a group known as cable bacteria, a peculiar collective of microbes that arrange themselves end-to-end in filamentous structures to facilitate long-distance electron transport.
Only a handful of these organisms were previously known, categorized within two candidate genera, Ca. Electrothrix and Ca. Electronema, neither of which have been successfully cultured in the lab nor formally described until now.
These bacteria thrive in oxygen-variable sedimentary environments, orchestrating a unique division of labor within their long, thread-like colonies.
Cells buried deep in the oxygen-deprived sediment generate energy by metabolizing sulfide, producing electrons that are then conducted along the bacterial filaments to the oxygen-rich upper layers, where other cells utilize oxygen or nitrate to receive them.
However, even within this unusual group, Ca. Electrothrix yaqonensis exhibits distinctive characteristics. According to microbiologist Cheng Li, associated with both Oregon State University and James Madison University, this new species appears to represent an early branch within the Ca. Electrothrix lineage.
This positioning suggests it could be pivotal in understanding the evolutionary trajectory and diverse functional roles of cable bacteria in various environments.
“This new species seems to be a bridge, an early branch within the Ca. Electrothrix clade, which suggests it could provide new insights into how these bacteria evolved and how they might function in different environments,” explained Dr. Li.
He further highlighted its unique traits: “It stands out from all other described cable bacteria species in terms of its metabolic potential, and it has distinctive structural features, including pronounced surface ridges, up to three times wider than those seen in other species, that house highly conductive fibers made of unique, nickel-based molecules.”
The research team, led by microbiologist Anwar Hiralal from the University of Antwerp in Belgium, meticulously isolated and characterized Ca. Electrothrix yaqonensis using a suite of advanced techniques, including genomic sequencing, morphological analysis, spectroscopy, and electrical characterization.
Their findings not only revealed morphological differences and genetic similarities to both existing candidate genera but also highlighted the presence of prominent surface ridges and extracellular sheaths produced by the bacteria as they form their extended, interconnected strands.
These strands enable the bacteria to perform crucial reduction-oxidation reactions across distances of up to several centimeters.
The researchers emphasize the potential for harnessing this natural electrical conductivity for human benefit, particularly in areas like food safety and environmental remediation.
“These bacteria can transfer electrons to clean up pollutants, so they could be used to remove harmful substances from sediments,” noted Dr. Li. “Also, their design of a highly conductive nickel protein can possibly inspire new bioelectronics.”
The discovery opens exciting avenues for future research, promising to refine the placement of Ca. Electrothrix yaqonensis within the cable bacteria family tree and further elucidate its unique properties. The research team concluded in their publication in Applied and Environmental Microbiology that the “non-conformist metabolic traits highlight the complex evolutionary dynamics within the cable bacteria clade and suggest a broader functional and ecological diversity within this clade than previously recognized.”
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