How parasitic archaea modify their hosts from within

NIOZ’s microbiologists have found that certain parasitic microbes, particularly a group known as DPANN archaea, not only feed on their hosts, but also alter the host’s metabolism and biology. Their study reveals that these archaea selectively consume certain lipids from their hosts, and thus the hosts may alter their metabolic processes.

A research team consisting of Su Ding, Joshua Hamm, Nicole Bale, Jaap Damsté and Anja Spang recently published these findings. Natural communication Article.

Understanding Archaea

Archaea are a distinct group of single-celled organisms that, like bacteria, lack a nucleus. DNA, or other organelles within their cells. The study focuses on DPANN archaea, which are characterized by their small cell size and limited genetic material. These archaea depend on other microbes for survival, attach to them, and extract lipids to build their own cellular membranes.

Electron microscopy showing parasitic Ca. Enha antarcticus: Small round shape, attached to its host, Hrr. lacus profundi. Credit: Joshua N Hamm

Selected food

Contrary to the earlier belief that these parasitic archaea indiscriminately ingest any fatty material from their hosts for their membranes, recent findings by Ding and Ham indicate a highly selective behavior. Specifically, parasitic archaea candidate Nanohaloarchaeum antarticus selectively synthesizes only certain lipids from its host, The halo of the deep lake. As Hamm summarizes, “In other words: K. N. Antarctica is a picky eater.”

Archaea, bacteria and higher organisms

Archaea are single-celled organisms that were long believed to be a specific group of bacteria. Like bacteria, they do not have a nucleus with DNA or other organelles inside their cells. However, by the 1970s, microbiologists no longer considered archaea bacteria, but classified them as a separate domain within all life forms. So, we now have archaea, bacteria and eukaryotes, the latter including all animals and plants, which have a nucleus containing the genetic material in their cells.

Host adaptations for parasitic activity

By analyzing the lipids of hosts with and without parasites, Ding and Ham were able to show that hosts adapt to the presence of parasites by altering their membranes. Altering both the types and amounts of lipids used and modifying the lipids to alter their behavior can lead to increased metabolism and a more elastic membrane that is harder for the parasite to penetrate. According to Hamm, this can have serious consequences for the host. „If the host’s membrane changes, it can influence how these hosts respond to environmental changes, for example in temperature or acidity,” he explains.

Another example of parasitic Ca. Enha Antarcticus is attached to its host, Hrr. lacus profundi. Credit: Joshua N Hamm

Revolutionary analytical techniques

Another exciting aspect of this research is the development of a new analytical technique by Su Ding at NIOZ. Previously, lipid analysis required prior knowledge of the lipid groups to be targeted. Ding’s new technique allows simultaneous examination of all lipids, including unknown types, to detect changes in lipid composition. „If we had used a classical approach, we wouldn’t have been able to see the changes in the lipids, but the new approach did that directly,” says Hamm.

Microbial ecological implications

These findings provide deeper insights into microbial interactions and ecology. „This not only sheds a first light on the interactions between different archaea; it provides completely new insight into the fundamentals of microbial ecology,” Hamm notes. He emphasizes the importance of future research to determine how these interactions may affect the stability of microbial communities under changing environmental conditions.

Reference: Su Ding, Joshua N. Hamm, Nicole J. Bale, Job S. Chinning Tamesday and Anja Spong, 22 April 2024, “Selective lipid recruitment by an archaeal DPANN symbiont from its host” Natural communication.
DOI: 10.1038/s41467-024-47750-2