'Completely Unexpected': Never-before-seen Species of Chlamydia Bacteria Discovered Deep Below Arctic Ocean

New species of chlamydia bacteria have been discovered buried in several feet of marine sediment nearly two miles below the surface of the Arctic Ocean, researchers have announced.

The team, from Uppsala University, Sweden, and the University of Bergen, Norway, came across the bacteria during an expedition to collect sediment samples from Loki's Castle—a field of active marine hydrothermal vents in a section of the Mid-Atlantic Ridge, between Norway and Greenland.

The bacteria were found to be thriving, despite extremely high-pressure, a lack of oxygen and an apparent absence of host organisms, according to a study published in the journal Current Biology.

"Finding Chlamydiae in this environment was completely unexpected, and of course begged the question what on earth were they doing there?" Jennah Dharamshi, lead author of the study from Uppsala University, said in a statement.

Chlamydiae are a large group of bacteria that survive by interacting with other organisms, ranging from microscopic amoeba, to plants and animals. This group includes species that are known to cause sexually transmitted infections in humans and other animals, such as koalas.

However, the diversity, ecology and biology of Chlamydiae bacteria remain severely understudied—and most of our knowledge of these species comes from lab studies. So the researchers decided to collect sediment samples from Loki Castle in an attempt to address this knowledge gap. The location was chosen based on the results of a previous study, which indicated that Chlamydiae bacteria might be present.

"We found a wide diversity of new Chlamydiae, perhaps well over a hundred. It is a bit hard to pinpoint this number exactly, as the definition of 'a species' is rather difficult," Thijs Ettema, another author of the study, from Uppsala, told Newsweek. "The discovered Chlamydia-related bacteria are only distantly related to the human pathogens. They share a common ancestry that dates back several hundred million years, and perhaps well over a billion years for some of the discovered lineages."

According to the researchers, the findings provide a better understanding of how the Chlamydiae evolved, how they developed their current behaviors, and even how they became pathogens of humans.

"The discovery of this expanded diversity in deep marine sediments was rather surprising, because we did not expect to find Chlamydiae in this type of environment," Ettema said. "All previous studies have pointed out that Chlamydiae need a host organisms in order to survive, and these host organisms are absent in the marine sediments we sampled. Our work would represent the first indication that Chlamydiae are able to survive outside of a host organism."

The researchers say the results suggest that these Chlamydiae might have a larger role in the marine ecosystem than previously thought.

"We have found that the group Chlamydiae is much more diverse that previously assumed, and they also have a more diverse lifestyle than previously thought—being able to live outside of a host organism," Ettema said. "Given their abundance in some of the samples we examined, these Chlamydiae might have a significant ecological impact on the environment they live in."

The Mid-Atlantic Ridge is a vast underwater mountain chain that stretches for about 10,000 miles along the middle of the Atlantic Ocean, from the Arctic to near the southern tip of Africa.

Stock image: Artist's illustration of a chlamydia bacterium. iStock