Researchers from the University of Nebraska-Lincoln in the US have discovered the first organism to survive on a diet of viruses, which is a sort of freshwater plankton.
Viruses are frequently ingested inadvertently by a variety of animals, and some marine protists may actively season their diet with viruses. However, for viruses to be considered a legitimate component of the food chain (referred to as virovory), they must provide their consumer with a sizable amount of energy or nutrients.
A common genus of protist known as Halteria is a microorganism that is known to flit about as its hair-like cilia drive it through the water. In addition to consuming chloroviruses introduced into its environment, the large virus fed Halteria’s growth and boosted its population in laboratory samples of the ciliate.
The cascading effects of extensive chlorovirus intake in the wild may have a significant effect on the carbon cycle. Chloroviruses are known to attack microscopic green algae and cause their hosts to disintegrate, releasing carbon and other nutrients into the environment. Serious virus-eating may be restricting this process.
According to ecologist John DeLong of the University of Nebraska-Lincoln, “if you multiply a rough estimate of how many viruses there are, how many ciliates there are, and how much water there is, it comes out to this huge amount of energy flow up the food chain.”
Our understanding of the global carbon cycling should be dramatically altered if this is occurring on the scale that we believe it to be.
The three-year-old study was inspired by the hypothesis that the abundance of viruses and bacteria in water may likely result in the consumption of the former by the latter, despite the fact that there were few prior studies to which the researchers could refer.
If you’re an organism hunting for food, viruses contain nutrients like amino acids, nucleic acids, lipids, nitrogen, and phosphorus. The researchers reasoned that something would undoubtedly want to use that as food.
To investigate if any animals regarded the viruses as food rather than a danger, the scientists injected chloroviruses to samples of pond water that they had collected. They eventually came across Halteria and Paramecium, two aquatic organisms that were prospering.
The Paramecium’s sizes and populations barely changed as it munched on the viruses. In contrast, Halteria consumed them and used the chlorovirus as a food source. In two days, the ciliate population increased by around 15 times, whereas the viral population shrank by 100 times.
According to DeLong, “At first, it was simply a hint that there were more of [the Halteria creatures].” But eventually, they grew large enough for me to be able to count them by grabbing a few with a pipette tip and dropping them into a clean drop.
Before being introduced to the two different types of plankton, chlorovirus DNA was marked with fluorescent green dye. The vacuoles, which are microorganisms’ equivalent of stomachs, were glowing green from the feeding, which proved that the viruses were being consumed.
The team had greater proof of what was going on when further investigation indicated that the ratios seen in other tiny predator vs. prey relationships in aquatic environments mirrored the expansion of Halteria in comparison to the fall of the Chlorovirus.
There is still a great deal to discover here. The researchers will then examine how Virovores may impact the food web, species evolution, and population resilience. However, they must first acquire proof that it occurs in the wild.
DeLong explains his motivation: “I wanted to know if this was bizarre or if it fit. “This is normal. Simply said, no one was aware of it.”
We must now go investigate whether this is true in nature.
The study has been made public in PNAS.