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Hot fungi from Chernobyl
Volume 15, Part 2, May 2001
Hot Fungi from Chernobyl The explosion that destroyed Unit No.4 of the Ukraine's Chornobyl Nuclear Power Plant on 26 April 1986 was catastrophic in many respects. Since it happened there has been considerable and varied scientific interest, not least as regards the microbiology of the unique conditions of the site. Subsequent to the accident, internal samples have been collected to assay potential microbial damage by fungi and other microbes to the remains of the Unit and its sarcophagus. An extensive technical report by Zhdanova, N. N., Zakharenchenko, V. A. Vember, V. V. & Nakonechnaya, L. T. entitled "Fungi from Chernobyl: mycobiota of the inner regions of the containment structures of the damaged reactor" appeared in Mycological Research 104 (2000); 1421-1426, and included illustrations of some of the fungi found there. This is a very important addition to the literature on this Ukrainian disaster and one which we feel readers of the Mycologist should be made aware of. The following account, therefore, gives the essence of the report and is compiled mostly from the Abstract and Discussion of that report. Extensive fungal growth was detected on the walls and other building constructions comprising the inner parts of the shelter of the damaged fourth unit of the Chornobyl [in Russian, Chernobyl] nuclear power plant in 1997-98 and constituted 37 species in 19 genera, of which Mucor plumbeus and Chaetomium globosum were, respectively, the only zygomycete and ascomycete. The rest were deuteromycetes. Two fungi commonly found were Cladosporium sphaerospermum and Penicillium hirsutum. Five others that were often encountered were Alternaria alternata, Aspergillus versicolor, Acremonium strictum (Fig 1), Aureobasidium pullulans (Fig 1) and Cladosporium herbarium, but most of the others were found only once. Four other species isolated from the shelter were recorded from the Ukraine for the first time: Penicillium ingelheimense, Phialophora melinii, Doratomyces stemonitis, and Sydouiia polyspora (Fig 2). In some places, complex associations of closely-growing fungi were found, including Penicillium chrysogenum, Stachybotrys chartarum and Chrysosporium pannorum (Fig 3).
Associations of Penicillium hirsutum with Cladosporium cladosporioides and Alternaria alternata (Fig 4) and other such 'communities' occurred in some circumstances. Nevertheless, of the total of 37 species, 29 were found only once. Comparison of the species growing under both severe and relatively weak radioactive contamination revealed a dominance of melanincontaining species in contaminated sites. The authors surmised that species such as C. sphaerospermum, P hirsutum, A. alternata, A. versicolor, and A. pullulans are potentially active biodestructors of even extremely radioactive substrates because they were constantly isolated from those substrates during the 18 months of sampling. According to their calculations, the radiation doses received by these strains must reach hundreds of Sieverts, at a minimum. The annual dose received by these fungi is at least 10' times the natural background radiation experienced in most places in the world (1-3 mSv y- I). For comparison, between 2 and 10 Sv in a short-term dose would cause severe radiation sickness in humans with increasing likelihood that this would be fatal; 20 mSv y- i averaged over 5 years is the international limit for nuclear industry employees. They note that Durrel & Schields (Mycologia 43 (1961); 636-641) observed a preponderance of dark-pigmented fungi after the conclusion of nuclear testing at Bikini atoll and refer to their own reports, in Russian, of numbers of micromycetes having been isolated from the highly radioactive soils in the immediate vicinity of the Chornobyl power plant, especially in the first years after the accident; they also mention records of active fungal growth in cooling water systems of nuclear reactors. The authors quote reports of microbial damage to, and destruction of, other concrete and ferro-concrete constructions where various deuteromycete fungi are present and damage to the concrete surface has been monitored. The principal characteristic of the Chornobyl shelter is the high flux of radioactivity. About 80% of the fungi recovered were melanin-containing and pigmented micromycetes. The authors believe this may correlate with the ability of these fungi to tolerate such high levels of
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Volume 15, Part 2, May 2001
Figs 1-4 Examples of cultures of species and associations found in the fourth Unit at Chernobyl. Fig 1 Acremonium strictum and Aureobasidium pullulans, often found in the inspected locations. Fig 2 Sydowia polyspora (the first record for Ukraine) from within the fourth Unit. Fig 3 Penicillium chrysogenum, Stachybotrys chartarum, Chrysosporium pannorum associations isolated from cable passages. Fig 4 The association consisting of Penicillium hirsutum, Cladosporium cladosporioides and Alternaria alternata isolated from locations with weak contamination.
radiation, not only to survive but to grow actively for lengthy periods of time. Most of the species they isolated were soil and plant litter saprotrophs, although Botrytis cinerea, Fusarium oxysporum, and F solani are also facultative plant pathogens. They suggest that the fungal contamination of walls and other parts of the building construction may occur as a result of spore laden external air streams penetrating into these locations. The plurality of pigmented species,especially those containing melanin, and the wide range of species isolated, further suggests that particular sub-populations are being selected.
The authors end by stating that the ecological evaluation of the shelter's mycobiota will continue as the systematic monitoring of the fabric of the building proceeds, and that they are also investigating what genetic modifications may have occurred in the fungi which are viable under such extreme conditions of radioactive contamination. For a general follow-up report on the area and history's worst nuclear accident see: Edwards, M. (1994) Chornobyl. National Geographic 186: 100115.
R. T. Moore
Hot Fungi from Chernobyl The explosion that destroyed Unit No.4 of the Ukraine's Chornobyl Nuclear Power Plant on 26 April 1986 was catastrophic in many respects. Since it happened there has been considerable and varied scientific interest, not least as regards the microbiology of the unique conditions of the site. Subsequent to the accident, internal samples have been collected to assay potential microbial damage by fungi and other microbes to the remains of the Unit and its sarcophagus. An extensive technical report by Zhdanova, N. N., Zakharenchenko, V. A. Vember, V. V. & Nakonechnaya, L. T. entitled "Fungi from Chernobyl: mycobiota of the inner regions of the containment structures of the damaged reactor" appeared in Mycological Research 104 (2000); 1421-1426, and included illustrations of some of the fungi found there. This is a very important addition to the literature on this Ukrainian disaster and one which we feel readers of the Mycologist should be made aware of. The following account, therefore, gives the essence of the report and is compiled mostly from the Abstract and Discussion of that report. Extensive fungal growth was detected on the walls and other building constructions comprising the inner parts of the shelter of the damaged fourth unit of the Chornobyl [in Russian, Chernobyl] nuclear power plant in 1997-98 and constituted 37 species in 19 genera, of which Mucor plumbeus and Chaetomium globosum were, respectively, the only zygomycete and ascomycete. The rest were deuteromycetes. Two fungi commonly found were Cladosporium sphaerospermum and Penicillium hirsutum. Five others that were often encountered were Alternaria alternata, Aspergillus versicolor, Acremonium strictum (Fig 1), Aureobasidium pullulans (Fig 1) and Cladosporium herbarium, but most of the others were found only once. Four other species isolated from the shelter were recorded from the Ukraine for the first time: Penicillium ingelheimense, Phialophora melinii, Doratomyces stemonitis, and Sydouiia polyspora (Fig 2). In some places, complex associations of closely-growing fungi were found, including Penicillium chrysogenum, Stachybotrys chartarum and Chrysosporium pannorum (Fig 3).
Associations of Penicillium hirsutum with Cladosporium cladosporioides and Alternaria alternata (Fig 4) and other such 'communities' occurred in some circumstances. Nevertheless, of the total of 37 species, 29 were found only once. Comparison of the species growing under both severe and relatively weak radioactive contamination revealed a dominance of melanincontaining species in contaminated sites. The authors surmised that species such as C. sphaerospermum, P hirsutum, A. alternata, A. versicolor, and A. pullulans are potentially active biodestructors of even extremely radioactive substrates because they were constantly isolated from those substrates during the 18 months of sampling. According to their calculations, the radiation doses received by these strains must reach hundreds of Sieverts, at a minimum. The annual dose received by these fungi is at least 10' times the natural background radiation experienced in most places in the world (1-3 mSv y- I). For comparison, between 2 and 10 Sv in a short-term dose would cause severe radiation sickness in humans with increasing likelihood that this would be fatal; 20 mSv y- i averaged over 5 years is the international limit for nuclear industry employees. They note that Durrel & Schields (Mycologia 43 (1961); 636-641) observed a preponderance of dark-pigmented fungi after the conclusion of nuclear testing at Bikini atoll and refer to their own reports, in Russian, of numbers of micromycetes having been isolated from the highly radioactive soils in the immediate vicinity of the Chornobyl power plant, especially in the first years after the accident; they also mention records of active fungal growth in cooling water systems of nuclear reactors. The authors quote reports of microbial damage to, and destruction of, other concrete and ferro-concrete constructions where various deuteromycete fungi are present and damage to the concrete surface has been monitored. The principal characteristic of the Chornobyl shelter is the high flux of radioactivity. About 80% of the fungi recovered were melanin-containing and pigmented micromycetes. The authors believe this may correlate with the ability of these fungi to tolerate such high levels of
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•
Volume 15, Part 2, May 2001
Figs 1-4 Examples of cultures of species and associations found in the fourth Unit at Chernobyl. Fig 1 Acremonium strictum and Aureobasidium pullulans, often found in the inspected locations. Fig 2 Sydowia polyspora (the first record for Ukraine) from within the fourth Unit. Fig 3 Penicillium chrysogenum, Stachybotrys chartarum, Chrysosporium pannorum associations isolated from cable passages. Fig 4 The association consisting of Penicillium hirsutum, Cladosporium cladosporioides and Alternaria alternata isolated from locations with weak contamination.
radiation, not only to survive but to grow actively for lengthy periods of time. Most of the species they isolated were soil and plant litter saprotrophs, although Botrytis cinerea, Fusarium oxysporum, and F solani are also facultative plant pathogens. They suggest that the fungal contamination of walls and other parts of the building construction may occur as a result of spore laden external air streams penetrating into these locations. The plurality of pigmented species,especially those containing melanin, and the wide range of species isolated, further suggests that particular sub-populations are being selected.
The authors end by stating that the ecological evaluation of the shelter's mycobiota will continue as the systematic monitoring of the fabric of the building proceeds, and that they are also investigating what genetic modifications may have occurred in the fungi which are viable under such extreme conditions of radioactive contamination. For a general follow-up report on the area and history's worst nuclear accident see: Edwards, M. (1994) Chornobyl. National Geographic 186: 100115.
R. T. Moore