‘Viriboles’ Found: Microorganisms That Survive on a Virus-Only Diet

Viruses are misunderstood. In the shadow of the COVID-19 pandemic, few look kindly on these protein-wrapped hodgepodges of genetic material that straddle dark links between the living and the non-living.

Viruses share some common features with living organisms, such as genome ownership and replication capacity, but are not self-persistent. In other words, viruses depend on infecting host cells in order to replicate. Viruses do not eat these cells. In fact, viruses have no metabolism. It simply hijacks host cells and reprograms them into miniature factories that produce more virus particles. In the process, it often causes injury or death to its host.

But what if the virus could sustain an entire population instead of destroying it?

In a new paper published in the Proceedings of the National Academy of Sciences (PNAS), researchers report evidence that microbes can sustain themselves and increase their populations by eating viruses. The groundbreaking discovery Showed “energetic” first — virus-only diet.

Viruses in ecosystems

Despite their small size, viruses can have a profound impact on ecosystems. Viruses can influence which organisms survive and which perish, often by causing massive host death. Many ecologists consider viruses to be predators of sorts, even at the top of the food chain (although, as mentioned above, viruses don’t treat their hosts like “food”).

John DeLong of the University of Nebraska, lead author of the study, wondered whether viruses, like other predators, could fall prey to anything else. I had a group of viruses in mind. In 2016, he participated in a landmark study investigating chloroviruses (viruses that infect freshwater algae). Given the abundance of chloroviruses in freshwater, DeLong thought something must be consuming them.

“Everyone should want to eat them…surely something has learned to eat these really good ingredients,” said DeLonge. statementViruses are a healthy snack, sure. They’re not only rich in amino acids, but they’re also rich in nitrogen and phosphorous – components of a hearty diet.

find the bilibore

To investigate, DeLong and his team created a simple study design. They collected water samples from a pond near the University of Nebraska. They isolated a variety of microbes that they thought could consume the virus, and added only chlorovirus to the mixture, so the microbes only have the virus as a potential food source. waited to see if the population of

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Ultimately, the researchers focused on two genera of protists common in freshwater ecosystems. Harteria When Paramecium. Since these microbes live in the same habitat as chloroviruses, it seemed likely that they may have evolved a way to consume the virus as food. If researchers can prove that, they’ll have compelling evidence that these protists are able to sustain themselves in an energetic lifestyle.

both within 2 days Harteria When Paramecium reduced the abundance of chlorovirus by a factor of 100, Harteria We increased the number and increased the population by 15 times. Harteria It converted approximately 17% of the mass of the consumed chlorovirus into new mass of itself.This is similar to values ​​reported when protists consumed bacteria as food. Harteria The cells ate about 10,000 to 1,000,000 viruses per day.When scaled up, this means that a single pond ciliate can be viably consumed a thousand trillion Virus every day in a small pond.

The team also tagged the viral DNA with a green fluorescent dye. Under proper lighting, they found that vacuoles (like tiny “stomachs” inside protists) contained chlorovirus.

New connections in the food chain

Food web analysis attempts to understand how energy flows from one organism to another within an ecosystem. Each food chain represents one path that nutrients and energy follow as they move through an ecosystem or wider food web. Previous food web analyzes assumed that the resources (carbon, nitrogen, and phosphorus) contained in viruses remained sequestered and did not move through the food web. In other words, they hypothesized that the virus “hides” nutrients in particles that nothing else could eat. But this experiment shows that assumption is probably wrong. As the authors write, this “virus-derived energy” likely rises through the aquatic food web, affecting its structure and dynamics.

like a protist Harteria They are at the bottom of the food chain and are important prey for zooplankton. Protists and zooplankton together make up a significant portion of living biomass and contribute enormous amounts of energy to the food web. Current models do not include trophic links between viruses and their consumers, thus ignoring important interactions and miscalculating trophic transfer of energy across specific ecosystems.

Since the study was completed, DeLong and his team have found other ciliates that can thrive on virus-only diets. need to do it. If so, the discovery could revolutionize our understanding of microbial ecosystems.