3.1 Introduction

Despite extreme conditions, the different Antarctic ecosystems and their substrata present themselves as natural habitats, occupied and colonised by several fungal species that range from the endemic to the cold-adapted cosmopolitan fungi. Among the substrates/microhabitats present in Antarctica, to date, soils have been the most studied ecosystem regarding the richness and diversity of fungi present (Tubaki and Asano 1965; Boyd et al. 1966; Heal et al. 1967; Sun et al. 1978; Bailey and Wynn-Williams 1982; Baublis et al. 1991; Vishniac 1996; Onofri et al. 2004; Adams et al. 2006; Fell et al. 2006; Ruisi et al. 2007; Bridge and Spooner 2012; Rao et al. 2012; Godinho et al. 2015; Gomes et al. 2018). Various studies of mycology in Antarctic soils have been conducted in the last decades with the objective of knowing the communities of fungi present and understanding their interactions and importance in the different terrestrial ecosystems of the region (Sun et al. 1978; Fletcher et al. 1985; Kerry 1990; Vishniac 1996; Marshall 1998; Onofri et al. 2000; de Hoog et al. 2005; Fell et al. 2006; Malosso et al. 2006; Arenz and Blanchette 2009).

Different types of soils are found in Antarctica; diversity is basically associated with the role of climatic variability, lithology, and biological colonisation (French 2007). In this region, different microclimates reflect environmental differences between its maritime and continental portions (French 2007). The Antarctic sea forms a climatic zone that surrounds the continent, covering archipelagos and part of the Antarctic Peninsula, and presents less severe climatic conditions, higher temperatures, and greater precipitation in water (Campbell and Claridge 1987; Simas et al. 2007, 2008). These conditions allow the development of deeper soil and greater vegetation cover (Campbell and Claridge 1987). In continental Antarctica, the climatic conditions are more severe, exemplified by the lower temperatures in relation to the peninsular region, and characterised by almost no precipitation (Green et al. 1999; Pannewitz et al. 2003). Therefore, the soils of the continental area are less developed and more stony and may have accumulation of salts as a marked characteristic (Delpupo et al. 2017).

The major fungal communities found in Antarctic soils include species belonging to phyla Ascomycota, Basidiomycota, Glomeromycota, traditional Zygomycota, and Chytridiomycota (Lawley et al. 2004; Onofri et al. 2004; Malosso et al. 2006; Fell et al. 2006; Ruisi et al. 2007; Arenz and Blanchette 2009; Arenz and Blanchette 2011; Bridge and Spooner 2012; Arenz et al. 2014; Pudasaini et al. 2017; Gomes et al. 2018).

The most represented orders of fungi in the soils are Onygenales, Eurotiales, Mortierellales, Mucorales, Saccharomycetales, Thelebolales, and Helotiales (Newsham et al. 2018). The resident fungi already identified in the Antarctic soil have different essential ecological roles as decomposers, pathogens, parasites, and mutualists (Swift et al. 1979; Yergeau et al. 2007; Upson et al. 2009; Lindo and Gonzalez 2010; Tedersoo et al. 2014). According to Newsham et al. (2015), with potential warming of the Antarctic regions, especially the peninsula areas, the Antarctic soils may be heavily colonised by fungi, suggesting a tendency towards an increase of 20–27% richness of various species in the southernmost soils by the end of the twenty-first century. Thus, in the coming years, there is a propensity for the discovery of new species and expansion of the geographical distribution of fungi along Antarctica, as well as for a more detailed understanding of their ecological relationships because of possible climatic changes in the region.

Besides the significant ecological importance, the fungi present in the Antarctic soils have also been studied as a source of bioproducts for biotechnological use. According to Santiago et al. (2012), because much of Antarctica still represents a preserved, primitive, and geographically isolated natural environment, some species of fungi inhabiting the region may have new and/or unique metabolic pathways capable of generating useful substances in different biotechnological processes with potential applications in the food, medicine, and agricultural industries.

3.2 The Antarctic Soils

Only 0.35% (45,000 km2) of Antarctica possesses ice-free areas, in which conditions for soil formation are verified (Bockheim 2015). These ice-free areas occur in continental and maritime Antarctica, with emphasis on the South Shetland archipelago and the Antarctic Peninsula, as well as the dry valleys of the Transantarctic Mountains (Bockheim and Ugolini 2008; Bockheim 2015). In maritime Antarctica, the sea has higher temperatures and precipitation than the continental Antarctica, resulting in the formation of deeper and more developed soils. Physical weathering is favoured in both the regions by the action of freezing and thawing cycles, whereas the presence of water in a liquid (unfrozen) state in austral summers as well as biological activity is predominant in the maritime region, which favours chemical weathering (Simas et al. 2006, 2007). Among the main processes of soil formation in Antarctica are the translocation (movement) of clays, cryoturbation, sulphurisation, podzolisation, phosphatisation, and salinisation. The pedological diversity is related mainly to the diversity of the material of origin, to different types of rocks and sediments, to the biological processes, and to the occurrence and distribution of the permafrost (Simas et al. 2008; Moura et al. 2012). Permafrost is defined as a thermal condition wherein the substrate temperature is below 0 °C for two or more consecutive years (Muller 1943; Van Everdingen 1998; French 2007). Associated with permafrost, an active layer can be termed as a layer that undergoes freezing and thawing and represents the highest expression of cryoturbation processes.

The main soil classes occurring in Antarctica are arenosols/neosols, cryossolos/gelisols, leptosols, gleysols, and cambisols. The relationship among these different classes is limited, and the terrain in which they occur is narrow, mainly owing to the dynamics and recent exposure of the source material. The cryossolos is characterised by the presence of permafrost up to 1 or 2 m deep when gellic features (vertical orientation of gravels, buried horizons, soils with patterns) are present. They occur in diverse environments, notably in moraines, geoforms related to cryoturbation, and gelifluction because of raised marine platforms, presenting a well-developed structure. Recent exposure and constant reworking of the source material favours the formation of leptosols (shallow or stony) with an incipient structure, these being more common in raised platforms and are closely related to residual landforms. The gleysols are found close to thaw channels and in depressions with slopes, being commonly present in the gleanings of the subsurface horizons in cryossolos because of the impediment of drainage caused by the presence of permafrost. The neosols (often sandy) occur at low altitudes, especially on the sea terraces, smooth slopes, and deposits (tills and flood plains), and show little or no structural development, small horizon differentiation, absent cryoturbation, and no diagnostic horizon. Cambisols are characterised by a finer texture and moderate structure; they do not present permafrost or cryoturbation and occur at low altitudes, in marine platforms, and in erosive features or deposits.

Some soils of extremely important scientific and environmental interest occur in Antarctica and are testimonies of the pedodiversity of this region of the earth. Among these soils, we highlight the ornithogenic soils, soils with patterns, sulphide soils and the desert soils. Ornithogenic soils are particularly abundant in maritime Antarctica, associated with phosphatisation process that comprises interaction between the substrate (rocks and sediments) and guano deposited by birds (Tatur and Myrcha 1984; Myrcha et al. 1985; Tatur and Barczuk 1985; Tatur 1989; Myrcha and Tatur 1991; Schaefer et al. 2004; Simas et al. 2007; Pereira et al. 2013). These soils are among the most developed soils in Antarctica and represent very important areas for biological dissemination and fixation (Fig. 3.1). In fact, on some of these soils, the development of an oasis with extensive vegetation cover shows a very high microbiological activity, comparable to that observed in a temperate zone (Myrcha et al. 1985). The development of vegetation in areas more distant from the coast (near nests of birds) indicates the importance of the fertilisation of soils by these faunae in establishing more complex vegetal communities and with greater capacity of fixation of C (Michel et al. 2006).

Fig. 3.1
figure 1

Ornithogenic soils. (a) Pygoscelis adeliae colonies, (b) guano pool formed by the accumulation of penguin droppings at the base of the snow accumulation, and (c) ornithogenic soil profile enriched in phosphorus. The photographs were taken on Harmony Point peninsula, Nelson Island, South Shetland Archipelago, maritime Antarctica. (Photo credits, LH Rosa and FS de Oliveira)

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Patterned ground is one of the most distinct formations in permafrost areas of the polar regions (Hallet et al. 2011). Patterned ground (or polygonal soils) occurs in ice-free areas by periglacial processes (French 2007). Patterned ground is a general term for any soil surface exhibiting a symmetric, discernible, and ordered pattern of the morphology of the terrain and, when present, of the vegetation (Fig. 3.2). Although not limited to permafrost regions, patterned ground formations develop best in areas affected by permafrost, either in recent times or in the bygone years. Such soils are direct products of cryoturbation processes. The process of the occurrence of high concentration of fine grains in the soils of periglacial environments (besides ornithogenic soils) is identified. The upward displacement of the thin material at the centre is caused by freezing and thawing (frost heave) of the ice lenses at the top and bottom of the active layer; the downward displacement at the borders is a gravity-induced movement (Mackay 1979).

Fig. 3.2
figure 2

Soils with pattern. (a) rock garlands with strong orientation of rock fragments, (b, c) mud boil pattern, showing the separation between coarse rock fragments (garland) and fine sediments (in the centre of the circle), and (d, e) abrupt contact between the stone garland and the fine particle concentration zone. The photographs were taken on the Harmony Point peninsula, Nelson Island, South Shetland Archipelago, maritime Antarctica. (Photo credits, FS de Oliveira)

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Sulphated soils are characterised by a genesis related to the presence of rocks rich in sulphides (Francelino et al. 2011). The oxidation of these minerals is related to their exposure to the atmosphere, generating particular geochemical conditions. For example, a change from sulphide to sulphate leads to an increase in Eh-pH causing acidity, which in turn leads to the formation of sulphated minerals (by sulphurisation/thiomorphism) (Krauskopf 1979). These minerals, such as jarosite, give a yellowish colour to the soils (Fig. 3.3), and therefore the areas of maritime Antarctica in which they occur are known as Yellow Points. Although the presence of sulphide rocks has also been verified in continental Antarctica, the sulphurisation was observed in an incipient way according to Delpupo et al. (2017).

Fig. 3.3
figure 3

Sulphated acids alone. (a) Outcropping of a pyritised andesite shaft with oxidised surface (yellow colour) enveloped by beach pebbles capped by ferruginous film (red colour), (b) saprolite (pyrrhotite andesite rock), and (c) acid soil profile of sulphated soil, in an area known as Yellow Point. The photographs were taken off the Keller Peninsula, King George Island, South Shetland Archipelago, maritime Antarctica. (Photo credits, d FS de Oliveira)

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As a pedological marker of areas of continental Antarctica with extreme aridity and even more intense cold, soils have been designated as polar desert soils (Bockheim 1990; Bockheim and Ugolini 1990). The soils of this region are skeletal to shallow, with poorly developed structures and lighter colours (Fig. 3.4). Salinisation is a remarkable process and is related not only to the climatic conditions but also to the drainage conditions of the slopes and the role of the winds, which commonly act in the formation of stony pavements by wind erosion of surface fines.

Fig. 3.4
figure 4

Polar desert soils. (a) Polar desert environment with stony desert pavement, (b) details of rock fragments of a stony desert pavement, and (c) profile of polar desert enriched in salt. The photographs were taken in the dry valleys of Edson Hills, Ellsworth Mountains (Delpupo et al. 2017), and continental Antarctica. (Photo credits, FS de Oliveira)

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3.3 Diversity of Fungi in Antarctic Soils

There are records that suggest the presence of fungi in Antarctica in the Permian (Paleozoic), Triassic, and Jurassic (Mesozoic) periods as demonstrated by the studies of Stubblefield and Taylor (1983), Taylor and White (1989), Taylor and Osborne (1996), Harper et al. (2012), and Arenz et al. (2014). Most of the species of fungi found in Antarctic soils are cold-adapted cosmopolitan fungi and also those that are considered endemic (Arenz et al. 2014), among which many have a high potential for colonisation and dispersion (Marshall 1998). In the last decades, there has been an increase in the understanding of the microbial diversity present in the Antarctic soils. Satellite images showed that 0.35% of Antarctica’s 45,000 km2 area is free of ice and has different types of exposed soils (Cowan et al. 2014), which are potential microhabitats for different communities of resident fungi.

The different types of Antarctic soils seem to harbour different communities of fungi, according to their physicochemical characteristics. Studies of fungi on Antarctic soils have uncovered the presence of diversified assemblies, which is demonstrated by the diversity, richness, and dominance indexes of the taxa identified (Table 3.1). In addition, according to Cowan et al. (2014), certain taxa dominate the communities of the different Antarctic habitats, such as Pseudogymnoascus destructans, Pseudogymnoascus appendiculatus, Penicillium tardochrysogenum, Penicillium verrucosum, Mortierella antarctica, Mortierella alpina, Rhodotorula mucilaginosa, Mortierella amoeboidea, Antarctomyces pellizariae, Aspergillus flavus, Aspergillus niger, Mrakia frigida, and Thelebolus globosus (Arenz and Blanchette 2011; Alias et al. 2013; Marfenina et al. 2016; Gomes et al. 2018; Kochkina et al. 2019).

Table 3.1 Examples of fungal diversity present in soils from different regions of the Antarctic Peninsula and continental Antarctica
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3.4 Major Genera of Fungi Present in Antarctic Soils

Different species and genera of fungi have been reported in the Antarctic soils (Table 3.2), among which are the cosmopolitan and endemic taxa. Among the genera most found in Antarctic soils are Penicillium, Aspergillus, Cladosporium, Mortierella, Antarctomyces, Pseudogymnoascus (synonymous Geomyces), Rodothorula, and Cryptococcus (Wicklow 1968; Mercantini et al. 1989; Stchigel et al. 2001; Arenz et al. 2006; Margesin et al. 2007; Bensch et al. 2010; Melo et al. 2014; de Menezes et al. 2017; Gomes et al. 2018).

Table 3.2 Species of fungi present in Antarctic soils
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Aspergillus is a cosmopolitan genus, being commonly isolated from soil and plants (Arenz et al. 2014; Godinho et al. 2015). In Antarctica, species of Aspergillus were isolated from ornithogenic soil (Wicklow 1968). Cladosporium is one of the biggest genera having a worldwide distribution and includes saprobic and parasitic species (Bensch et al. 2010). Although some species of Cladosporium are known to be present only in specific hosts or have a restricted geographic distribution (Meyer et al. 1967), they are one of the dominant genera found in the dry valley soils of Antarctica (Arenz et al. 2006).

Mortierella is a genus that occurs in different types of substrates (Kirk et al. 2008). Species of Mortierella isolated from Antarctic soils correlated with moss (Frate and Carreta 1990; Tosi et al. 2002; Melo et al. 2014), rhizosphere D. antarctica, and C. quitensis, found in varied soils of the Antarctic Peninsula (Bridge and Newsham 2009; Gomes et al. 2018; Wentzel et al. 2018). The species Mortierella antarctica has already been isolated from samples of different soils (Frate and Carreta 1990; Zucconi et al. 1996; Adams et al. 2006; Gomes et al. 2018). According to Onofri et al. (2004) and Melo et al. (2014), M. antarctica has an acid (linoleic acid and arachidonic acid) production capacity, which is important for its development at low temperatures; therefore, it is able to grow and sporulate at 0 °C (Onofri et al. 2004). The genus Antarctomyces, which is considered to be a psychrophilic and endemic species of Thelebolales, was isolated from the Antarctic soil (Stchigel et al. 2001) and represents the first species of the genus described.

Pseudogymnoascus has a wide geographical distribution in cold ecosystems (www.mycobank.org), including Antarctic soils (Mercantini et al. 1989; Arenz and Blanchette 2011; Godinho et al. 2015; Gonçalves et al. 2015; Gomes et al. 2018). Mercantini et al. (1989) and Arenz et al. (2006) have reported that this genus plays an important role in the decomposition and recycling of organic matter in Antarctica. Among the species of Pseudogymnoascus found in Antarctica, Pseudogymnoascus destructans is phylogenetically close to those species that attack bats in North America and Europe/Palearctic Asia. It is obtained from several soils of different islands of Antarctica as reported by Gomes et al. (2018), suggesting that Antarctic soil may be a natural habitat for this species.

The genus Rhodotorula comprises basidiomycetous yeasts isolated from different substrates (Nagahama et al. 2001; Libkind et al. 2003; Butinar et al. 2005; Margesin et al. 2007; Sampaio 2011; de Garcia et al. 2012). Rhodotorula mucilaginosa is a cosmopolitan species that occurs in aquatic soils and habitats (Kurtzman et al. 2011). In Antarctica, R. mucilaginosa was already reported to be present in the soil (Ray et al. 1989; Vishniac, 1996; Pavlova et al. 2001). According to Shivaji and Prasad (2009), Cryptococcus, which had some of its species reclassified as Naganishia, Torula, and Vishniacozyma by Liu et al. (2006), is the genus of yeast most abundant on the Antarctic continent and is frequently distributed in different places and substrates. The species of Cryptococcus that have already been isolated from different Antarctic soils are Torula laurentii (Cryptococcus laurentii) and Vishniacozyma victoriae (Cryptococcus victoriae) (Vaz et al. 2011; Sousa et al. 2017).

3.5 Correlation of the Physicochemical Characteristics of Fungi with Antarctic Soils

Fungi perform a function of early colonisation of sites, develop soil structure and transform nutrients into bioavailable forms. In addition, fungi seem to be one of the main agents in the driest Antarctic soils to synthesise sterols required by invertebrates present in the soil (Connell et al. 2006). Soil biology plays a key role in determining soil carbon; the composition of species of the primary carbon-regulating communities can affect the entry of carbon into terrestrial ecosystems (Newsham et al. 2018).

Antarctic soils have the capacity of autotrophic carbon fixation and nitrogen fixation (Hopkins et al. 2006; Cowan et al. 2011; Cameron et al. 2012). The competition between fungi for carbon sources can influence the efflux of CO2 in the soil, leading to a decrease in efficiency of the use of carbon, which can further affect the carbon rate present in soils (Newsham et al. 2018). It is possible that these fungi mineralise the soil and consume the generated nutrients. The abundance of cultivable fungi in the soil can be correlated with carbon and nitrogen, suggesting that nutritional limitations in highly oligotrophic environments are prime factors in determining the distribution and abundance of native fungi (Connell et al. 2006). The results obtained by Newsham et al. (2018) suggest that the carbon rate found in warm Antarctic soils has increased, which may be caused by taxa of different microorganisms, including fungi. Different organic compounds have different fixation times in the soil and are degraded by specific taxa of saprophytic fungi (Newsham et al. 2018).

3.6 Conclusion and Perspectives

Despite the different and extreme conditions, the Antarctic soils shelter various genera and species of fungi, whether be they are cold-adapted cosmopolitan fungi or endemic. Studies on Antarctic soils have increased in recent years, and these demonstrate that there is a great diversity of genera and species present in different types of soils, many of which may be new to science. Further research is needed to increase knowledge about the fungal diversity associated with different types of soils in Antarctic environments, especially in areas where there are progressive thaws in the Antarctic Peninsula, leading to exposing of soils not yet studied along with their resident fungal communities. An interesting point that needs to be investigated in the future is the correlation of physicochemical characteristics found in soils with diversity, ecological function, and potential biotechnological applications of Antarctic fungi, which could ultimately elucidate the intrinsic characteristics of each genus and species.