Chernobyl fungus could shield astronauts from cosmic radiation
A recent study tested how well the fungi species Cladosporium sphaerospermum blocked cosmic radiation aboard the International Space Station.
03 August, 2020
Medmyco / Wikimedia Commons
- Radiation is one of the biggest threats to astronauts' safety during long-term missions.
- C. sphaerospermum is known to thrive in high-radiation environments through a process called radiosynthesis.
- The results of the study suggest that a thin layer of the fungus could serve as an effective shield against cosmic radiation for astronauts.
<p>When astronauts return to the moon or travel to Mars, how will they shield themselves against high levels of cosmic radiation? A recent experiment aboard the International Space Station suggests a surprising solution: a radiation-eating fungus, which could be used as a self-replicating shield against gamma radiation in space.</p><p>The fungus is called <em>Cladosporium sphaerospermum</em>, an extremophile species that thrives in high-radiation areas like the Chernobyl Nuclear Power Plant. For <em>C. sphaerospermum</em>, radiation isn't a threat — it's food. That's because the fungus is able to convert gamma radiation into chemical energy through a process called radiosynthesis. (Think of it like photosynthesis, but swap out sunlight for radiation.)</p><p>The <a href="https://en.wikipedia.org/wiki/Radiotrophic_fungus#:~:text=Radiotrophic%20fungi%20are%20fungi%20which,into%20chemical%20energy%20for%20growth." target="_blank">radiotrophic fungus</a> performs radiosynthesis by using melanin — the same pigment that gives color to our skin, hair and eyes — to convert X- and gamma rays into chemical energy. Scientists don't fully understand this process yet. But the study notes that it's "believed that large amounts of melanin in the cell walls of these fungi mediate electron-transfer and thus allow for a net energy gain."</p>
<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzUzMDY1Mi9vcmlnaW4ucG5nIiwiZXhwaXJlc19hdCI6MTYyODExMzQwMH0.rY29j4PRZdxDnQNoZOC1uvl7fJBog0pIcAN-Mo32hO8/img.png?width=980" id="8dbfa" class="rm-shortcode" data-rm-shortcode-id="73d903cc5cb4beb22a981516510260b4" data-rm-shortcode-name="rebelmouse-image" alt="Petri dishes containing fungi" />
Shunk et al.
<p>Additionally, the fungus is self-replicating, meaning astronauts would potentially be able to "grow" new radiation shielding on deep-space missions, instead of having to rely on a costly and complicated interplanetary supply chain.</p><p>Still, the researchers weren't sure whether <em>C. sphaerospermum</em> would survive on the space station. Nils J.H. Averesch, a co-author of the <a href="https://www.biorxiv.org/content/10.1101/2020.07.16.205534v1.full.pdf" target="_blank">study published on the preprint server bioRxiv</a>, told <a href="https://www.syfy.com/syfywire/fungus-that-eats-radiation-could-be-cosmic-ray-shield" target="_blank">SYFY WIRE</a>:</p><p style="margin-left: 20px;">"While on Earth, most sources of radiation are gamma- and/or X-rays; radiation in space and on Mars (also known as GCR or galactic cosmic radiation) is of a completely different kind and involves highly energetic particles, mostly protons. This radiation is even more destructive than X- and gamma-rays, so not even survival of the fungus on the ISS was a given."</p><img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzUzMDY2Mi9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY1NzM2MTk5OX0.9itVRaQ-O18I3xhLKLMV-TU9JPqGKUAcr2CRcOB0TEo/img.jpg?width=980" id="9c5dd" class="rm-shortcode" data-rm-shortcode-id="4bf6b4d563e31ec1427c5146680611b3" data-rm-shortcode-name="rebelmouse-image" alt="Fungus in dish" />
C. sphaerospermum
<p>To test the "radio-resistance" of <em>C. sphaerospermum</em> in space, petri dishes containing a .06-inch layer of the fungus were exposed to cosmic radiation aboard the ISS. Dishes containing no fungus were exposed, too. The results showed that the fungus cut radiation levels by about 2 percent.</p><p>Extrapolating these results, the researchers estimated that a roughly 8-inch layer of <em>C. sphaerospermum</em> "could largely negate the annual dose-equivalent of the radiation environment on the surface of Mars." That would be a significant benefit to astronauts. After all, an astronaut who is one year into a Mars mission would have been exposed to roughly 66 times more radiation than the average person on Earth.</p><img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzUzMDY2My9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY1NzY3MzI0OH0.OKgKmgz2ffz7bCiU7B9Yeal_ia1wXPzcHZPOupZurGg/img.jpg?width=980" id="b07eb" class="rm-shortcode" data-rm-shortcode-id="9b0508619697790cb1e5ff2e4239d174" data-rm-shortcode-name="rebelmouse-image" alt="ISS" />
International Space Station
NASA
<p>To be sure, the researchers said more research is needed, and that <em>C. sphaerospermum</em> would likely be used in combination with other radiation-shielding technology aboard spacecraft. But the findings highlight how relatively simple biotechnologies may offer outsized benefits on upcoming space missions.</p><p style="margin-left: 20px;">"Often nature has already developed blindly obvious yet surprisingly effective solutions to engineering and design problems faced as humankind evolves – C. sphaerospermum and melanin could thus prove to be invaluable in providing adequate protection of explorers on future missions to the Moon, Mars and beyond," the researchers wrote.</p>
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Say goodbye to the beloved banana
Those bananas you love are Cavendish bananas, and they're probably about to go extinct.
29 July, 2020
Credit: Shutter Chiller/Shutterstock
- The world's most popular edible variety is about to be wiped out by a fungal invader. Again.
- We've already lost Gros Michel bananas, which were the world's favorite until the 1960s.
- The solution? Possibly genetic editing, but more likely a greater availability of exotic varieties.
<p>They're certainly among the most convenient fruits. Bananas are compact, tidy, bundles of potassium and deliciousness. And when we says "bananas," what we really mean are Cavendish bananas, an edible, cultivated subgroup of the fruit. Ninety-nine percent of the bananas sold in the world are seedless Cavendish bananas, although in the wild there are over a thousand strains of bananas, many of which are unsuitable for eating. Unfortunately, Cavendish bananas are about to go extinct.</p>
Cavendish clones and T4
<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzUyMTAyOC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYxOTMyODExOX0.VYcEq9r5NtWoNOk9P4-ueQ_qOP95x3t7tlEEZnSxcgw/img.jpg?width=980" id="381dd" class="rm-shortcode" data-rm-shortcode-id="a007a0ab6d2efae7e4d5dab3b12de480" data-rm-shortcode-name="rebelmouse-image" alt="painting of William Spencer" />The father of our preferred banana
Image source: Sotheby's/Wikimedia
<p>Cavendish bananas are pretty much genetically identical — they're all sterile clones from the fruit of a single English tree, grown in 1834 by William Cavendish, the 6th Duke of Devonshire, in his greenhouse. As such, they're all vulnerable to the same threats. What's killing them now is a soil-borne fungus, <em><a href="https://apsjournals.apsnet.org/doi/10.1094/PHYTO-04-15-0101-RVW" target="_blank">Fusarium oxysporum</a> f.sp. cubense</em> (Foc), also known as Fusarium Wilt Tropical Race 4 (TR4). It kills bananas by infecting its root and vascular system, rendering it unable to take in critical minerals and water.</p><p>TR4 first began ruining Cavendish bananas in Malaysia and Indonesia <a href="https://www.newsweek.com/worlds-bananas-are-clones-and-they-are-imminent-danger-publish-monday-5am-1321787#:~:text=The%20entire%20banana%20industry%20was,for%20export%20to%20developed%20countries." target="_blank">around 1990</a> and has since made its way through Southeast Asia and to the Middle East and Africa. Last year, it reached Latin America, the world's main source of bananas.</p><p>Growers are doing what they can to beat back T4's advance—including taking acre to use only untainted planting materials so as to avoid spreading T4 via soil contamination—and Australia has shown some success in slowing down the assault. However, these are stopgap efforts that are ultimately unlikely to save the Cavendish.</p>Not Fusarium oxysporum’s first rodeo
<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzUyMTAzOC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYwNTk4NjAzNH0.nvv9tta7mEBQKk-kJg0u8sb-Ujej7xw5asXwgpCEneY/img.jpg?width=980" id="2ee9f" class="rm-shortcode" data-rm-shortcode-id="8a804a4b17901a4ac3c5bc05b36b7451" data-rm-shortcode-name="rebelmouse-image" alt="fungus growing in petri dish" />Fusarium oxysporum
Credit: Keith Weller, USDA-ARS - USDA/Wikimedia
<p>This is not the banana industry's first encounter with this fungus. Up to the 1960s, the world's most popular edible banana was the Gros Michel, or "Big Mike," variety. To meet worldwide demand, growers got into the Gros Michel monoculture business big-time, with thousands of tropical-forest hectares converted into massive plantations growing these bananas.</p><p>What spelled doom for the Gros Michel banana was, yes, <em>Fusarium oxysporum</em> — the disease it caused was known as "Fusarium Wilt," or "Panama Wilt." It was the T1 version of today's T4, and it largely wiped out the Gros Michel banana, nearly taking the entire banana industry down with it. (You can <a href="https://www.atlasobscura.com/articles/gros-michel-bananas" target="_blank">still find a Gros Michel banana</a>, but it's not easy.)</p><p>The Cavendish didn't quite have Gros Michel's rich taste, but it wasn't vulnerable to T1, and so it took the place of the Gros Michel as the world's main edible banana. </p>Not the first rodeo for the Cavendish
<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzUyMTA0Mi9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYzMDYzODI4M30.3Jqr-ls6ELY-oxnpNzxBzR81L6c9IJxUCnBmptuRqMY/img.jpg?width=980" id="d7948" class="rm-shortcode" data-rm-shortcode-id="a5d6bf71bdf5aa5f7af96a2e81ccb871" data-rm-shortcode-name="rebelmouse-image" alt="A banana leaf with Black Sigatoka" />A banana leaf with Black Sigatoka
Credit: Scot Nelson/Wikimedia
<p>The Cavendish is also susceptible to another fungal invader via a disease called <a href="https://en.wikipedia.org/wiki/Black_sigatoka" target="_blank">Black Sigatoka</a>. This fungus, <em>Pseudocercospora fijiensis</em>, destroys the plants' leaves, producing cell death that damages the plants' ability to photosynthesize. If left uncontrolled, crop yields can be reduced by 35 to 50 percent.</p><p>Growers are fighting back with continual leaf trimming and the liberal use of fungicides—more than 50 applications of the toxic chemicals may be required each year to bring Black Sigatoka under control. This is, of course, harmful to workers managing the crops and to the environment, and makes growing Cavendish bananas less profitable. If this weren't bad enough, repeated applications of fungicides end up strengthening the fungus and making it even harder to control by selecting for mutations that can withstand the chemicals.</p>Fixing the Cavendish?
<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzUyMTA0Ni9vcmlnaW4uZ2lmIiwiZXhwaXJlc19hdCI6MTYyNjcxNTc1M30.ppCOY7UAcqXyCq2vIkGSBtei2pOBrmV_jf57XwbfJtY/img.gif?width=980" id="e5011" class="rm-shortcode" data-rm-shortcode-id="28a14854a86c9cc7cbf12276342d2b00" data-rm-shortcode-name="rebelmouse-image" /><p>There <em>is</em> <a href="https://www.washingtonpost.com/national/health-science/bananapocalypse-the-race-to-save-the-worlds-most-popular-fruit/2017/10/06/bf1635ac-7d28-11e7-83c7-5bd5460f0d7e_story.html" target="_blank">one field full of healthy Cavendish bananas</a> and T4, however. It's in the town of Humpty Doo in Australia. Researchers led by <a href="http://staff.qut.edu.au/staff/dale/" target="_blank">James Dale</a> of Queensland University of Technology inserted a gene from a wild banana into their Cavendish bananas and that did the trick. Big Think readers may recognize Dale's name—he is also part of the team developing the so-called "golden banana," a fruit packed with vitamin A that could help reduce world hunger. We've written about this <a href="https://bigthink.com/robby-berman/whats-so-special-about-a-golden-banana" target="_self">intriguing project</a> before. </p><p>Other scientists also see hope for the Cavendish via genetic editing, whether that's by activating existing genes or by de-activating genes that misbehave in the presence of T4. Would you eat a genetically modified banana? Many wouldn't, and it's therefore unlikely that genetically modified Cavendish bananas will reach the worldwide market in time, especially considering the extended testing for safety that various governments would require.</p>Hope for the banana-lover
<p>Some observers are already looking beyond the Cavendish in hopes that we might end up with an even better fruit, given the many varieties of banana that exist in nature. Two such bananas are Peru's popular <a href="http://www.promusa.org/blogpost617-Peru-s-best-kept-banana-secret" target="_blank">Isla banana</a> and the <a href="https://www.housebeautiful.com/room-decorating/outdoor-ideas/a27285401/blue-java-bananas-ice-cream-banana-tree/" target="_blank">Blue Java</a>, a banana that tastes like ice cream. Maybe the demise of the Cavendish will end up being a good thing.</p>
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