Solar UV-B Radiation Inhibits the Growth of Antarctic Terrestrial Fungi

Abstract

We tested the effects of solar radiation, and UV-B in particular, on the growth of Antarctic terrestrial fungi. The growth responses to solar radiation of five fungi, Geomyces pannorum, Phoma herbarum, Pythium sp., Verticillium sp., and Mortierella parvispora, each isolated from Antarctic terrestrial habitats, were examined on an agar medium in the natural Antarctic environment. A 3-h exposure to solar radiation of >287 nm reduced the hyphal extension rates of all species relative to controls kept in the dark. Pythium sp. cultures exposed to solar radiation for 1.5 h on five consecutive days were most sensitive to radiation of >287 nm, but radiation of >313 nm also inhibited growth to a lesser extent. Radiation of >400 nm had no effect on hyphal growth relative to controls kept in the dark. Short-wave solar UV-B radiation of between 287 and 305 nm inhibited the growth of Pythium sp. hyphae on and below the surface of the agar medium after 24 h, but radiation of >345 nm only reduced the growth of surface hyphae. Similar detrimental effects of UV-B on surface and, to a lesser extent, submerged hyphae of all five fungi were shown in the laboratory by using artificial UV-B from fluorescent lamps. A comparison of growth responses to solar radiation and temperature showed that the species that were most resistant to UV radiation grew fastest at higher temperatures. These data suggest that solar UV-B reduces the growth of fungi on the soil surface in the Antarctic terrestrial environment.

Ultraviolet photodegradation facilitates microbial litter decomposition in a Mediterranean climate

“…Second, we hypothesized that UV would preferentially degrade the lignin fraction in litter, as its aromatic structure is known to absorb UV wavelengths (Austin and Ballare´2010) and is thought to undergo chemical changes when exposed to solar radiation (Lanzalunga and Bietti 2000). Finally, we hypothesized that the net result of UV is inhibition of microbial activity, given previous observations that UV can damage microbial DNA (Rohwer and Azam 2000), slow the growth of microbial communities (Hughes et al 2003), and result in altered microbial community composition (Caldwell et al 2007). …”

“…Foereid et al (2010) found evidence for facilitation in a lab study, but field studies have yet to determine how UV affects microbial properties in litter. UV could have detrimental effects on microbial communities, as it is known to damage microbial DNA (Rohwer and Azam 2000) and suppress growth of terrestrial microbes (Hughes et al 2003). On the other hand, UV facilitation of microbial communities could be especially important in semiarid Mediterranean ecosystems with marked seasonality.…”

Diversity of microfungi in ornithogenic soils from Beaufort Island, continental Antarctic

“…The indigenous fungi of Antarctica have been studied in soils (Kerry 1990a, b, Finotti 1993, Azmi et Seppelt 1998, Hughes et al 2003, Krishnan et al 2011, ice cores and permafrost (Gilichinsky et al 2005), lake sediment (Sugiyama et al 1967) and also in the air column (Marshall 1997). Airborne spores originating from South America have also been detected in the Antarctic Peninsula region (Marshall 1997).…”

Effect of Voriconazole and Ultraviolet-A Combination Therapy Compared to Voriconazole Single Treatment on Fusarium solani Fungal Keratitis

“…In addition, only UV itself is known to have antifungal effects. 12,13 Based upon these considerations, we compared voriconazole single agent treatment with voriconazole plus UV-A combination therapy as a possible treatment for fungal keratitis.…”