Virus play an important role in Earth’s climate – they control their hosts like puppets.

According to Gary Truble, a soil virus ecologist. Viruses can actually impact the environment.





The hosts, in this case, aren’t people or animals: they are bacteria. A growing body of research is revealing how viruses manipulate what bacteria eat and how they guide the chemical reaction that sustains life.

When those changes happen to a lot of bacteria, the cumulative effects could potentially shape the composition and behavior of Earth’s ocean, soil, and air.





Viruses are basically genetic material packed in a protein shell. To produce, they attach to a living cell and inject their genetic material. Some viruses then linger in the cell, often stitching their own DNA into that of the host and being copied along with the host DNA when the cell divides.

At some in a typical viral life cycle, the virus hijacks the cell’s machinery to build new viruses, eventually causing the cell to burst and spill its infectious contents.





According to Jennifer Brum, an oceanographer at Louisiana State University in Baton Rouge, “if you go swimming in the ocean, that’s about 200 million viruses per every mouthful of seawater. And almost all of those ate to be infecting the 20 million bacteria in that same mouthful of seawater,”

Viral infections are ubiquitous parts of bacterial life. This is a big deal since bacteria recycle and transform the chemicals we eat and breath, when viruses kill bacteria, they release nutrients back into the environment.

Scientists have been finding that viruses also change what bacteria do while they’re alive?

Martha Clokie, a microbiologist from the University of Leicester in the UK, says “we live in a bacteria- driven world those bacteria are endlessly being subtly manipulated by viruses.”

In 2013, researchers identify a key photosynthesis gene called PsbA in the virus that infect cyanobacteria in the ocean. Like plants, cyanobacteria use photosynthesis to transform sunlight into usable energy, releasing oxygen as a by-product.

Follow up work by the Warwick team and other labs in the U.S and Israel showed how the viral PsbA gene allows photosynthesis to continue after a cell is infected, even though the bacteria’s own photosynthesis genes are shut down.





Infected cells can photosynthesize even faster than uninfected cells in bright sunlight.













What exactly are Cyanobacteria does?

Cyanobacteria are thought to produce one-quarter of all oxygen in the atmosphere. Researchers have estimated that half of these bacteria are infected with viruses at any given time, although that number is highly uncertain.





This could mean that one out of every eight breaths you take is made possible by the virus.





Usually, photosynthesis typically pulls carbon dioxide out of the air and water. However, the viruses in cyanobacteria suppress the steps of photosynthesis that bind up carbon dioxide into organic matter. That could mean that researchers have overestimated the power of ocean bacteria to clean up carbon dioxide.





Since the discovery of viral PsbA, researchers have found dozens of other genes in ocean viruses that are similar to metabolic genes in bacteria. They have guessed – for example, some of the genes look like they might help bacteria digest carbohydrates and fats, while others are likely to help bacteria collect scarce nutrients such as phosphate.





Viruses don’t do all this to be nice, but they do it make more viruses, some viruses can linger in their hosts for a long time before they begin producing new viruses. In the meantime, a virus needs its host alive, so the interests of the parasite and its victim may be temporarily aligned.





A cell that has a virus like that, when it’s just living under not very good conditions, will replicate faster it will flourish, but then it’s got this molecular time bomb inside it.









What are the shreds of evidence of found viruses?

Most of the evidence of viral puppeteers come from the ocean, but scientists are starting to find the same thing on land.

In 2018, researchers found in their two studies that genes for breaking down plant carbohydrates in viruses living in thawing permafrost’s soils in Sweden. That could mean that the viruses are helping their hosts digest carbohydrates such as hemicellulose and starch.





But strangely, the carbohydrates the viral genes targeted are too large to fit inside most bacteria, it’s doubtful whether bacteria could handle such large carbs even if they had the genes to break them down.





In an alternative scenario, the enzymes for breaking down unwieldy carbs might build up inside bacteria while they're infected. When the bacteria burst, they would release the enzymes along with all the new viruses.

The enzymes would then break down carbs in the environment. The broken-down carbs would provide food for new bacterial hosts infected with the virus's progeny -- a sort of viral version of parents providing for their offspring. This idea of viral parental care is still the only speculation.





Regardless of where the carbs are broken down, some of the simple sugars produced by this process will likely find their way into the wider environment, where many types of microbes can use them.





"It's like they're prepping meals for other organisms,"

Scientists have found viral genes for breaking down carbohydrates in numerous environments, including soils, oceans, lakes, human guts, and cow rumens (organs where bacteria help cows digest their food).





For instance, many viruses from aquatic environments have a gene for breaking down alginate, which is produced by algae. And in the human gut, there are viral genes for breaking down starch -- a common carb in human food -- and mucin, which makes up the mucus lining our digestive tracts.













In some cases, viruses might speed up bacteria's own digestion processes; in other cases, they might give bacteria the power to use new food sources that they couldn't digest on their own.





For example, an uninfected bacterium might just pass through the human gut. But once a virus gave it genes for digesting mucus and starch, it might stay and become part of the person's microbiome.





Scientists are not sure that viruses are playing in the global carbon cycle, but there is evidence that they are playing a very important role.





For example, if viruses are enabling bacteria in a cow's rumen to use the cow's mucus as food that could increase the amount of methane the cow belches out.





Similarly, viruses in the soil could be contributing to greenhouse gas emissions by helping decomposers break down dead plant material. Indeed, when Solden analyzed genetic data from soils, she found viral genes for breaking down two especially persistent plant carbohydrates, called xyloglucan and arabinogalactan that most microbes can't digest.

Whatever role viruses play in the climate, they have been doing it for millions of years. It's not as though they are going to suddenly wreck Earth's climate now that scientists have discovered them.





But human-caused climate change could disrupt the intricate balance between bacteria and viruses, changing how much carbon is released or taken up in ways we can't yet predict.

Warmer temperatures and more acidic oceans will likely favour some types of viruses over others and

influence how long viruses remain in their hosts before killing them.





Conclusion

Scientists predict on how things are going to change," "Now they’re finding more and more that we're going to have to include viruses within those predictive models to increase our ability to understand what's going to happen in the future."