Radiosynthesis (metabolism)

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Radiosynthesis is the theorized capture and metabolism, by living organisms, of energy from ionizing radiation, analogously to photosynthesis. Metabolism of ionizing radiation was theorized as early as 1956 by the Russian microbiologist S. I. Kuznetsov. [1]

Beginning in the 1990s, researchers at the Chernobyl Nuclear Power Plant uncovered some 200 species of apparently radiotrophic fungi containing the pigment melanin on the walls of the reactor room and in the surrounding soil. [2] [3] Such "melanized" fungi have also been discovered in nutrient-poor, high-altitude areas which are exposed to high levels of ultraviolet radiation. [4]

Following the Russian results, an American team at the Albert Einstein College of Medicine of Yeshiva University in New York began experimenting with radiation exposure of melanin and melanized fungi. They found that ionizing radiation increased the ability of melanin to support an important metabolic reaction, and that Cryptococcus neoformans fungi grew three times faster than normal. [5] [4] Microbiologist Ekaterina Dadachova suggested such fungi could serve as a food supply and source of radiation protection for interplanetary astronauts, who would be exposed to cosmic rays. [4]

In 2014, the American research group was awarded a patent for a method of enhancing the growth of microorganisms through increasing melanin content. The inventors of this process claimed their fungi were employing radiosynthesis, and hypothesized that radiosynthesis may have played a role in early life on Earth, by allowing melanized fungi to act as autotrophs. [6]

From October 2018 through March 2019, NASA conducted an experiment aboard the International Space Station to study radiotrophic fungi as a potential radiation barrier to the harmful radiation in space. Radiotrophic fungi have many possible applications on Earth as well, potentially including a disposal method for nuclear waste or use as high-altitude biofuel or a nutrition source. [7]

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<span class="mw-page-title-main">Radiation</span> Waves or particles moving through space

In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or a material medium. This includes:

<span class="mw-page-title-main">Melanin</span> Group of natural pigments found in most organisms

Melanin is a family of biomolecules organized as oligomers or polymers, which among other functions provide the pigments of many organisms. Melanin pigments are produced in a specialized group of cells known as melanocytes.

<span class="mw-page-title-main">Endolith</span> Organism living inside a rock

An endolith or endolithic is an organism that is able to acquire the necessary resources for growth in the inner part of a rock, mineral, coral, animal shells, or in the pores between mineral grains of a rock. Many are extremophiles, living in places long considered inhospitable to life. The distribution, biomass, and diversity of endolith microorganisms are determined by the physical and chemical properties of the rock substrate, including the mineral composition, permeability, the presence of organic compounds, the structure and distribution of pores, water retention capacity, and the pH. Normally, the endoliths colonize the areas within lithic substrates to withstand intense solar radiation, temperature fluctuations, wind, and desiccation. They are of particular interest to astrobiologists, who theorize that endolithic environments on Mars and other planets constitute potential refugia for extraterrestrial microbial communities.

<i>Cryptococcus neoformans</i> Species of yeast

Cryptococcus neoformans is an encapsulated yeast belonging to the class Tremellomycetes and an obligate aerobe that can live in both plants and animals. Its teleomorph is a filamentous fungus, formerly referred to Filobasidiella neoformans. In its yeast state, it is often found in bird excrement. Cryptococcus neoformans can cause disease in apparently immunocompetent, as well as immunocompromised, hosts.

<span class="mw-page-title-main">Effects of the Chernobyl disaster</span> Assessment of Chernobyls impact on Earth since 1986

The 1986 Chernobyl disaster triggered the release of radioactive contamination into the atmosphere in the form of both particulate and gaseous radioisotopes. As of 2024, it was the world's largest known release of radioactivity into the environment.

<i>Rhodotorula</i> Genus of fungi

Rhodotorula is a genus of fungi in the class Microbotryomycetes. Most species are known in their yeast states which produce orange to red colonies when grown on Sabouraud's dextrose agar (SDA). The colour is the result of pigments that the yeast creates to block out certain wavelengths of light (620–750 nm) that would otherwise be damaging to the cell. Hyphal states, formerly placed in the genus Rhodosporidium, give rise to teliospores from which laterally septate basidia emerge, producing sessile basidiospores. Species occur worldwide and can be isolated from air, water, soil, and other substrates.

<span class="mw-page-title-main">Mycelial cord</span> Structure produced by fungi

Mycelial cords are linear aggregations of parallel-oriented hyphae. The mature cords are composed of wide, empty vessel hyphae surrounded by narrower sheathing hyphae. Cords may look similar to plant roots, and also frequently have similar functions; hence they are also called rhizomorphs. As well as growing underground or on the surface of trees and other plants, some fungi make mycelial cords which hang in the air from vegetation.

<i>Setosphaeria rostrata</i> Pathogenic fungus

Setosphaeria rostrata is a heat tolerant fungus with an asexual reproductive form (anamorph) known as Exserohilum rostratum. This fungus is a common plant pathogen, causing leaf spots as well as crown rot and root rot in grasses. It is also found in soils and on textiles in subtropical and tropical regions. Exserohilum rostratum is one of the 35 Exserohilum species implicated uncommonly as opportunistic pathogens of humans where it is an etiologic agent of sinusitis, keratitis, skin lesions and an often fatal meningoencephalitis. Infections caused by this species are most often seen in regions with hot climates like Israel, India and the southern USA.

<span class="mw-page-title-main">Radiotrophic fungus</span> Fungus capable of radiosynthesis

Radiotrophic fungi are fungi that can perform the hypothetical biological process called radiosynthesis, which means using ionizing radiation as an energy source to drive metabolism. It has been claimed that radiotrophic fungi have been found in extreme environments such as in the Chernobyl Nuclear Power Plant.

<span class="mw-page-title-main">Fungus</span> Biological kingdom, separate from plants and animals

A fungus is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as one of the traditional eukaryotic kingdoms, along with Animalia, Plantae and either Protista or Protozoa and Chromista.

<i>Deinococcus radiodurans</i> Radioresistant extremophile species of bacterium

Deinococcus radiodurans is a bacterium, an extremophile and one of the most radiation-resistant organisms known. It can survive cold, dehydration, vacuum, and acid, and therefore is known as a polyextremophile. The Guinness Book Of World Records listed it in January 1998 as the world's most radiation-resistant bacterium or lifeform.

Exposure to ionizing radiation is known to increase the future incidence of cancer, particularly leukemia. The mechanism by which this occurs is well understood, but quantitative models predicting the level of risk remain controversial. The most widely accepted model posits that the incidence of cancers due to ionizing radiation increases linearly with effective radiation dose at a rate of 5.5% per sievert; if correct, natural background radiation is the most hazardous source of radiation to general public health, followed by medical imaging as a close second. Additionally, the vast majority of non-invasive cancers are non-melanoma skin cancers caused by ultraviolet radiation. Non-ionizing radio frequency radiation from mobile phones, electric power transmission, and other similar sources have been investigated as a possible carcinogen by the WHO's International Agency for Research on Cancer, but to date, no evidence of this has been observed.

<i>Exophiala dermatitidis</i> Species of fungus

Exophiala dermatitidis is a thermophilic black yeast, and a member of the Herpotrichiellaceae. While the species is only found at low abundance in nature, metabolically active strains are commonly isolated in saunas, steam baths, and dish washers. Exophiala dermatitidis only rarely causes infection in humans, however cases have been reported around the world. In East Asia, the species has caused lethal brain infections in young and otherwise healthy individuals. The fungus has been known to cause cutaneous and subcutaneous phaeohyphomycosis, and as a lung colonist in people with cystic fibrosis in Europe. In 2002, an outbreak of systemic E. dermatitidis infection occurred in women who had received contaminated steroid injections at North Carolina hospitals.

Black yeasts, sometimes also black fungi, dematiaceous fungi, microcolonial fungi or meristematic fungi is a diverse group of slow-growing microfungi which reproduce mostly asexually. Only few genera reproduce by budding cells, while in others hyphal or meristematic (isodiametric) reproduction is preponderant. Black yeasts share some distinctive characteristics, in particular a dark colouration (melanisation) of their cell wall. Morphological plasticity, incrustation of the cell wall with melanins and presence of other protective substances like carotenoids and mycosporines represent passive physiological adaptations which enable black fungi to be highly resistant against environmental stresses. The term "polyextremotolerance" has been introduced to describe this phenotype, an example of which is the species Aureobasidium pullulans. Presence of 1,8-dihydroxynaphthalene melanin in the cell wall confers to the microfungi their characteristic olivaceous to dark brown/black colour.

<i>Cladophialophora bantiana</i> Species of fungus

Cladophialophora bantiana is a melanin producing mold known to cause brain abscesses in humans. It is one of the most common causes of systemic phaeohyphomycosis in mammals. Cladophialophora bantiana is a member of the ascomycota and has been isolated from soil samples from around the world.

<span class="mw-page-title-main">Arturo Casadevall</span> Cuban-American scientist

Arturo Casadevall is a Bloomberg Distinguished Professor of Molecular Microbiology & Immunology and Infectious Diseases at the Johns Hopkins Bloomberg School of Public Health and Johns Hopkins School of Medicine, and the Alfred and Jill Sommer Professor and Chair of the W. Harry Feinstone Department of Molecular Microbiology and Immunology at the Johns Hopkins Bloomberg School of Public Health. He is an internationally recognized expert in infectious disease research, with a focus on fungal and bacterial pathogenesis and basic immunology of antibody structure-function. He was elected a member of the National Academy of Sciences in 2022.

<span class="mw-page-title-main">Bioremediation of radioactive waste</span>

Bioremediation of radioactive waste or bioremediation of radionuclides is an application of bioremediation based on the use of biological agents bacteria, plants and fungi to catalyze chemical reactions that allow the decontamination of sites affected by radionuclides. These radioactive particles are by-products generated as a result of activities related to nuclear energy and constitute a pollution and a radiotoxicity problem due to its unstable nature of ionizing radiation emissions.

<i>Cladosporium sphaerospermum</i> Species of fungus

Cladosporium sphaerospermum is a radiotrophic fungus belonging to the genus Cladosporium and was described in 1886 by Albert Julius Otto Penzig from the decaying leaves and branches of Citrus. It is a dematiaceous (darkly-pigmented) fungus characterized by slow growth and largely asexual reproduction. Cladosporium sphaerospermum consists of a complex of poorly morphologically differentiated, "cryptic" species that share many physiological and ecological attributes. In older literature, all of these sibling species were classified as C. sphaerospermum despite their unique nature. Accordingly, there is confusion in older literature reports on the physiological and habitat regularities of C. sphaerospermum in the strict sense. This fungus is most phylogenetically similar to C. fusiforme. According to modern phylogenetic analyses, the previously synonymized species, Cladosporium langeroni, is a distinct species.

Oidiodendron cereale is a species of ascomycetes fungi in the order Helotiales. This fungus is found globally in temperate climates where average summer temperatures are below 25 °C, but there have been scattered reports from tropical and subtropical environments. It is predominantly found in soil, but little is known regarding their ecological roles in nature. However, an enzymatic study from Agriculture Canada showed that O. cereale can break down a variety of plant, fungal, and animal based substrates found in soil, which may have beneficial effects for plants. On rare occasions, this fungus is found on human skin and hair. There has been one reported case of O. cereale infection in 1969, causing Neurodermitis Nuchae.

<span class="mw-page-title-main">Scytalone</span> Chemical compound

Scytalone or Scytolone is a cyclic beta hydroxy ketone substituted by hydroxy groups at positions 3, 6, and 8. It is a natural product found in various fungal species including Cytospora populina and Ceratocystis fimbriata.

References

  1. Kuznetsov, S. I. (March 1, 1956). "On the Question of Possibility of "Radiosynthesis"". Mikrobiologiya (in Russian). 25. OSTI   4367507.
  2. Zhdanova, N. N.; Vasilevskaya, A.I.; Artyshkova, L. V.; Sadovnikov, Y. S.; Lashko, T. N.; Gavrilyuk, V. I.; Dighton, J. (July 1994). "Changes in micromycete communities in soil in response to pollution by long-lived radionuclides emitted in the Chernobyl accident". Mycological Research. 98 (7): 789–795. doi:10.1016/S0953-7562(09)81057-5.
  3. Zhdanova, Nelli N.; Tugay, Tatyana; Dighton, John; Zheltonozhsky, Victor; Mcdermott, Patrick (September 2004). "Ionizing radiation attracts soil fungi". Mycological Research. 108 (9): 1089–1096. doi:10.1017/S0953756204000966. PMID   15506020.
  4. 1 2 3 Balter, Michael (May 23, 2007). "Zapped By Radiation, Fungi Flourish". Science. Retrieved 2 November 2017.
  5. Dadachova, Ekaterina; Bryan, Ruth A.; Huang, Xianchun; Moadel, Tiffany; Schweitzer, Andrew D.; Aisen, Philip; Nosanchuk, Joshua D.; Casadevall, Arturo (May 23, 2007). "Ionizing Radiation Changes the Electronic Properties of Melanin and Enhances the Growth of Melanized Fungi". PLOS ONE. 2 (5): e457. Bibcode:2007PLoSO...2..457D. doi: 10.1371/journal.pone.0000457 . PMC   1866175 . PMID   17520016.
  6. B2 USpatent 8652827 B2,Dadachova, Ekaterina; Bryan, Ruth; Casadevall, Arturo,"Radiosynthesis as an alternative energy utilization process in melanized organisms and uses thereof",published February 18, 2014, assigned to Albert Einstein College of Medicine of Yeshiva University
  7. "Experiment Details".