Bioweathering of chrysotile by fungi isolated in ophiolitic sites

Our plain-English summary of Bioweathering of chrysotile by fungi isolated in ophiolitic sites, by S. Daghino, E. Martino, E. Vurro, et al (FEMS Microbiology Letters, 2008).

The study

• Authors: S. Daghino, E. Martino, E. Vurro, M. Tomatis, M. Girlanda, B. Fubini, S. Perotto
• Journal: FEMS Microbiology Letters
• Published: 2008;285(2):242-9
• Cited by: 22 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Asbestos minerals are commonly found in serpentine rocks and because of the hazard to human health, research has recently focused on possible detoxification strategies. Some fungal species that inhabit serpentine sites (two disused chrysotile asbestos mines in the Western Alps) have been isolated and characterized in order to obtain data on their biodiversity and bioweathering abilities on chrysotile fibres. The three dominant species (Verticillium leptobactrum, Paecilomyces lilacinus and Aspergillus fumigatus) have proved to be able to actively remove iron from chrysotile fibres, V. leptobactrum being the most efficient. A wide range of serpentinicolous fungi release siderophores, iron-chelating compounds, that could play a role in iron extraction from fibres. Iron removal had been correlated previously with a decrease in the toxic potential of fibres, and a biotechnological application of fungi can be envisaged for asbestos detoxification.

In plain English

In this laboratory study, the authors collected rock and soil samples from two disused chrysotile asbestos mines in the Western Alps of Italy (19 at Balangero, four at Emarese) and grew the fungi living in them. They isolated 888 colonies (60 species) from Balangero and 796 colonies (38 species) from Emarese. Verticillium leptobactrum dominated at both sites. In plate tests, all tested strains except Trichoderma harzianum were good producers of siderophores, compounds that bind iron. Three dominant species, plus Fusarium oxysporum for comparison, were then grown in liquid culture with and without chrysotile fibres. With fibres present, iron in the culture liquid rose significantly for F. oxysporum, V. leptobactrum and Paecilomyces lilacinus, but not for Aspergillus fumigatus, whose growth the fibres inhibited. V. leptobactrum was the most active at removing iron. The study measured iron, not toxicity. Earlier work cited by the authors linked fungal iron removal to reduced fibre reactivity. The authors concluded that fungal weathering may be a possible tool for asbestos bioremediation, though further studies are needed under mesocosm and field conditions.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory study: isolation and identification of fungi from mine samples, a plate test for siderophore release, and liquid cultures of fungi with and without chrysotile fibres
• Who was studied: Fungi isolated from rock and soil samples from two disused asbestos mines in Italy: 19 samples from the San Vittore mine (Balangero, Turin) and 4 from the Settarme-Chassant mine (Emarese, Aosta)
• Exposure: Chrysotile fibres supplied by the company in charge of the Balangero mine, held in a dialysis membrane inside the fungal cultures; control cultures had no fibres
• Main results:
  • 888 colonies (CFUs) representing 60 species were isolated from Balangero samples, and 796 CFUs representing 38 species from Emarese samples
  • Verticillium leptobactrum dominated the fungal community at both mine sites
  • In the siderophore plate test, all tested strains except Trichoderma harzianum were good siderophore producers
  • Chrysotile fibres did not significantly change the growth of F. oxysporum, V. leptobactrum or P. lilacinus
  • Chrysotile fibres inhibited the growth of A. fumigatus
  • Iron dissolved in the culture liquid increased significantly with chrysotile present for F. oxysporum, V. leptobactrum and P. lilacinus, compared with controls. There was no significant change for A. fumigatus.
  • When iron was adjusted for fungal biomass, V. leptobactrum was the most active at removing iron
  • Iron stored inside the fungi did not change significantly with chrysotile present, except in A. fumigatus
  • The study measured iron removal from the fibres, not toxicity
• The authors' conclusion: The authors concluded that fungal weathering may be a possible tool for asbestos bioremediation, but that further studies are needed under mesocosm and field conditions
• Limitations the authors state:
  • Results were obtained in vitro; the authors state that further studies are needed under mesocosm and field conditions
  • Results for F. oxysporum were highly variable
  • The mechanism of iron removal is not settled; the authors say it is still under investigation

Mines named here

Asbestos mines this study is about. Each mine's page says who ran it, when it worked, and what it produced.

• Balangero mine, Balangero, about 20 km north of Turin, Piedmont

All asbestos mines

Topics

The National Library of Medicine indexes this study under subjects our site covers: Chrysotile.

Medical terms in this study, explained in our Lexicon: Chrysotile, Asbestos, Serpentine Group.

Related studies

• Soil fungi reduce the iron content and the DNA damaging effects of asbestos fibers — S. Daghino, F. Turci, et al. (2006)
• Fungal diversity is not determined by mineral and chemical differences in serpentine substrates — S. Daghino, C. Murat, et al. (2012)
• Solid-liquid Interface Screening SystemーApplication to the Screening of Antibiotic and Cytotoxic Substance-producing Fungi — S. Oda, S. Nomura, et al. (2019)
• Weathering of chrysotile asbestos by the serpentine rock-inhabiting fungus Verticillium leptobactrum — S. Daghino, F. Turci, et al. (2009)
• Siderophore-mediated iron removal from chrysotile: Implications for asbestos toxicity reduction and bioremediation — S.K. Mohanty, C. Gonneau, et al. (2018)
• Soil fungal hyphae bind and attack asbestos fibers — E. Martino, L. Prandi, et al. (2003)

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