ORIGINAL PAPER R. Bergero á M. Girlanda á G.C. Varese á D. Intili A.M. Luppi Psychrooligotrophic fungi from Arctic soils of Franz Joseph Land Accepted: 22 November 1998 Abstract Microfungi isolated from soil samples col- lected in Franz Joseph Land by means of the soil di- lution and soil washing methods were screened for their ability to grow at low temperatures. The oligotrophic ability of the psychrotrophic strains was then deter- mined on silica gel. A total of 40 taxa from 21 genera were isolated. Most isolates were species of Acre- monium, Geomyces, Mortierella, Phialophora, Phoma, Thelebolus and sterile fungi. Eutypella scoparia, Hy- phozyma variabilis and Ovadendron sulphureo-ochra- ceum are new records as soil and Arctic fungi. Most fungal isolates were psychrotrophic. The few psy- chrooligotrophs were species of Geomyces, Phoma, Thelebolus and Mortierella. Overall, our results suggest that the major component of an Arctic soil myco¯ora should be active in one or more short growing seasons interspersed with periods of prolonged dormancy. Only a minor component, such as the small group of psychrooligotrophic fungi found in this study, may be expected to show continuous slow growth. Introduction Arctic and Antarctic soils are regarded as stressed hab- itats. Low temperatures are the major stress factor that exerts a strong direct and indirect eect on microbial life processes by inducing dierent adaptation strategies and the establishment of psychrotrophic and psychrophilic forms. Low temperatures create other stress conditions. Water is biologically unavailable when frozen. Plant communities often form scanty and discontinuous cov- ers. Primary production, essentially devoted to bryo- phytes, lichens and to a lesser extent vascular plants, is reduced and concentrated in the short polar summer. In polar deserts and semideserts, roots, which account for 60±70% of the net primary production in soil (Fogel 1985; Newmann 1985), exhibit an extremely reduced development. Root:shoot ratios have been reported to be very low, ranging from 0.2 to 0.7 (Khodachek 1969; Aleksandrova 1970; Svoboda 1977; Bell and Bliss 1978). It is assumed that, due to the prevailing low nutrient conditions, fungi live in the soil as dormant propagules that burst when fresh organic matter enters the ecosys- tem. However, it has been proved that both fungi and bacteria withstand low nutrient conditions through their oligotrophic capabilities. Tribe and Mabadeje (1972) found that spores of some fungal species germinate and grow on nutrient-free media. Parkinson et al. (1989) and Barakah (1992), too, showed that fungi can grow in media containing very low concentrations of carbon and that oligotrophy is a general characteristic for soil fungi, but is mainly absent in wood-decomposing and my- corrhizal fungal species. In environments such as the semidesert and desert high Arctic and Antarctic, where primary production is greatly reduced, soil microorganisms experience not only physical stress, but also harsh oligotrophic conditions. The ability of the components of polar fungal commu- nities to grow in oligotrophic conditions has not yet been investigated. This study was undertaken to investigate the oligo- trophic abilities of Arctic psychrotrophic soil fungi. Two complementary isolation techniques were employed, as well as both carbon-rich and carbon-poor media to en- sure the recovery of a wide spectrum of fungi. Materials and methods Study area The area under investigation is located in Franz Joseph Land (latitude 79°50¢)81°50¢N), a high-arctic desert or semidesert Polar Biol (1999) 21: 361±368 Ó Springer-Verlag 1999 R. Bergero (&) á M. Girlanda á G.C. Varese á D. Intili A.M. Luppi Dipartimento di Biologia Vegetale dell'UniversitaÁ di Torino and CSMT-CNR, Viale P.A. Mattioli 25, I-10125 Turin, Italy e-mail: bergero@bioveg.unito.it; Fax: +39-11-6707459