Bacteria are found virtually everywhere, including dirt, hot springs, oceans, and even next to and inside other living things like humans. Although they are essentially invisible, they have a significant effect on almost every aspect of life on Earth.
Despite their abundance, surprisingly little is known about many microorganisms that have existed for billions of years.
This includes a variety of nano-sized bacteria called Omnitrophota. First discovered based on short fragments of DNA just 25 years ago, these bacteria are common in many environments around the world but have been poorly understood. Until now.
An international research team has performed the first large-scale analysis of more than 400 newly sequenced and extant Omnitrophota genomes, revealing new details about their biology and behavior. The team’s findings appear in the March 16 issue of the journal Nature Microbiology.
“We now have the most comprehensive look yet at the biology of an entire phylum of microorganisms and the surprising role they play in Earth’s ecosystems,” said UNLV microbiologist Brian Hedlund, corresponding author of the study. “There are a finite number of major lineages of life on our planet, and it’s exciting to learn more about the organisms that predated plants and animals and were basically hidden under our noses.”
The tricky thing about Omnitrophota is that they are still largely considered microbial dark matter, meaning they exist in nature but cannot yet be grown as a single species in laboratory studies. Only two species have been observed microscopically, and only very recently.
To present a comprehensive picture of their biology, the scientists compared 349 existing and 72 newly mapped Omnitrophota genomes. This included a review of publicly available data and new samples collected from geothermal environments, freshwater lakes, wastewater, groundwater and springs around the world.
The team found that, in most cases, Omnitrophota measure less than 450 nanometers, making them among the smallest known organisms. They also showed genetic markers consistent with symbiosis—probably as predators or parasites of other microorganisms, suggesting they would have high metabolic rates. When isotope uptake was measured as a proxy for metabolic activity, Omnitrophota was indeed hyperactive.
“Despite how little we collectively knew about Omnitrophota, microbial ecologists had long cited them. Our goal was to finally pull that line out of obscurity,” said Cale Seymour, a recent UNLV master’s graduate and lead author of the study. “The more we learn about their energy storage pathways and possible lifestyles, the closer we get to our goal of culturing them in the lab and bringing them into the light.”
Read Now:<strong>The fossil site is the “Rosetta Stone” for understanding early life</strong>
