1. Introduction

Antarctica represents a very attractive location to search for novel cold-adapted enzymes or bioactive compounds both for being a permanently cold environment and because of the minimum human-associated activity. The fungal component of Antarctic soils is mostly represented by few psychrophilic and many mesophilic-psychrotolerant and oligotrophic species well adapted to the Antarctic constrains^[1]. Some Antarctic soil fungi, in particular, have developed multiple mechanisms of stress tolerance, as the activation of peculiar metabolic pathways and the production of either enzymes active at temperatures below the common limits, or other bioactive compounds of great potential value for biotechnological applications^[2]. The search on fungi in Antarctica deserves to be improved, and the preservation of isolated strains in culture collections is mandatory, to have available wide and unique sources of new bioactive producers^[3].

2. Enzymes

Cold-adapted enzymes produced by psychrophilic or psychrotolerant microorganisms are an important element for the survival strategy in Antarctic ecosystems. In fact, if extremely low temperatures generally restrict microbial enzyme activity, cold-active enzymes can conduct transformations at lower temperatures than those produced by their mesophilic homologues. They display a high specific activity at low and moderate temperatures, associated with a relatively high thermosensitivity^[4]. These properties make them a potentially valuable alternative to their mesophilic counterparts in cold environments. They may represent an interesting advantage in large scale processes, that generally occur at higher temperatures, for reducing the energy costs associated with heating steps^[5][6]. In the meantime, the thermosensitivity provides the possibility of rapidly inactivating them by mild heat treatments, preserving in this way the product quality^[4]. Some hypotheses have been proposed to explain the cold adaptation of these enzymes compared to their mesophilic and/or thermophilic counterparts, and amino acid substitutions was supposed as a possible mechanism. These properties with regard to their current and possible applications in biotechnology have been reviewed by Marx et al.^[4]. Additionally, Antarctic enzymes often exhibit a wide range of pH and temperature optima^[7]. This latter property is strictly linked to wide, frequent and sudden temperature variations experienced by terrestrial surfaces, based on soil expositions and weather conditions. 

3. Other Bioactive Compounds

In addition to enzymes, fungi are a rich reservoir of different classes of secondary metabolites, such as terpenoids, polyketides, alkaloids, polyacetylenes with demonstrated antiviral, antibacterial, antifungal, antitumoral, herbicidal and antiprotozoal activities. These molecules play a pivotal role in the inter- and intra-specific interactions within the soil microbial communities and provide them competitive advantages over other microorganisms^[3][8].

Because of the recent emergence of antibiotic-resistant pathogenic microorganisms, and the connected risks for public health, the search for novel classes of active compounds in this context is worth to be developed for its strong practical importance, as it has been recognized by the World Health Organization as a threat to human health^[9][10]. Extreme environments could be an excellent source of new antibiotics and, in this context, Antarctica, an almost unknown continent, is potentially of great interest. An overview of secondary metabolites with versatile antimicrobial potential was reported by Bratchkova and Ivanova^[11] from Arctic and Antarctic microorganisms and their possible role in the adaptation and survival of microorganisms in the ice deserts was discussed. Some strains are good producers of secondary metabolites with multiple activities^[3].