‘Geomycology’ can be defined as the impact of fungi on geological processes, including the alteration and weathering of rocks and minerals, the accumulation of metals and their role in nutrient cycling and influence on proliferation of microbial communities in mineral substrates. Although many studies on microbial interactions with minerals have been published in recent years, the main focus of geomicrobiology has been on prokaryotes. Recently, it has become apparent that epi- and endolithic fungi comprise a significant component of the microflora in a wide range of rocks including siliceous types (silica, silicates and aluminosilicates), sandstone, granite, limestone, marble and gypsum. However, to date little is known about their in situ growth patterns or biogeochemical roles in such an environment. The aim of this article is to highlight our recent work on the biogeochemical roles of fungi inhabiting limestone (CaCO3) and dolomite (CaMg(CO3)2) rocks and to emphasise the importance of fungi as agents of geological change.

Names of fungi

1. Sclerotinia curreyana (Berkeley ex Currey) P. Karsten = Myriosclerotinia curreyana (Berkeley ex Currey) Buchwald; conidial state Myrioconium Sydow

2. Sclerotinia Fuckeliana (de Bary) Fuckel = Botryotinia fuckeliana (de Bary) Whetzel; conidial state Botrytis cinerea Persoon ex Fries

3. Sclerotinia fructigena (Persoon) Schröter = Monilia fructigena Honey ex Whetzel; conidial state Monilia fructigena (Persoon) Eaton

Introduction: Features of interest

Members of the Sclerotiniaceae are plant pathogens characterized by stalked apothecia with inoperculate asci. Apothecia arise from stromata, e.g. sclerotia which are formed on or in the tissue of the host plant. The apothecial state and the type of stroma are typical and taxonomically relevant features of the Sclerotiniaceae, and the family has been supported and delimited by DNA sequence data (Carbone & Kohn, 1993; Holst-Jensen et al., 1997a,b).

Fomitopsis officinalis (Vill.: Fr.) Bondartsev & Singer (Laricifomes officinalis) has a holarctic distribution in three large areas: West-Europe, North America, Ural-Siberia, and some small populations in Morocco (Maire, 1914; Malençon, 1955), China (Dai, 2000), Japan and Korea (Gilbertson & Ryvarden, 1986). Undoubtedly, the European as well as the West-Siberian populations are relicts, like their host populations, especially Larix spp. Branke (1896) suggested that the relict localities of F. officinalis on Larix deciduas Mill. in Poland can be recognized as evidence of continuous larch forest occupying large parts of the Europe during cold post-glacial periods. At present, the species is most common in Siberia from the foothills of the Ural Mountains to the shores of the Pacific Ocean (Murashkinskij, 1939; Bondartsev, 1953; Lyubarskij & Vassiljeva, 1975; Mikhaleva, 1993; Mukhin, 1993). It is rare also in North America (Overholts, 1953; Gilbertson, 1980).

The spine fungi, which grow on the trunks, branches and stumps of trees, produce strange but beautiful mushrooms. They belong to a genus called Hericium, and there are a number of species throughout the northern hemisphere. Amongst the best known are the ‘spine face’ (H. cirrhatum (Pers.: Fr.) Nikol.) which is branched with several, shell-shaped caps, and the ‘coral spine fungus’ (H. coralloides (Scop.: Fr.) Pers.) which lacks a cap but is highly branched and covered with small spines, up to 10 mm long. Although all the spine fungi are edible and generally delicious, most attention has been given to that known in China as the ‘monkey head’ (H. erinaceum Bull.: Pers.).

The behaviour of Suillia flies on basidiocarps of Hebeloma radicosum was studied in central Japan. Hebeloma radicosum is a peculiar fungus that fruits only on talpid mole middens, near the moles' nests. All insect species around selected basidiocarps of this mushroom species were observed, their behaviour studied, and identified in late October to early November 1992, and again briefly in 2001. During these periods, Suillia flies were seen on the basidiocarps, while other insect species were rarely observed. Usually one Suillia fly (male) occupied one basidiocarp and prevented other conspecifics from occupying the same basidiocarp. This appeared to be pre-mating territorial behaviour. Larval stages of Suillia are known to be mycophagous, and the territorial behaviour is presumably performed to defend oviposition sites. This is the first report from Asia on ecological aspects of Suillia flies.

Sunflower oil poured onto compost in November induced massive growth of Mortierella species. Mortierella hyaline was isolated into culture at 4 or 18 °C on weak media but not at 23-25 °C or on 2% malt agar. It grew well on olive oil agar, with its hyphae aggregating inside oil drops. The nature of nutrients utilized in normal soils and composts by Mortierella is not known but lipid levels there would appear to be low. Many Mortierella species are able to convert diverse carbon sources into lipids and are thus known as oleaginous fungi. Their biotechnological applications are briefly discussed.

Filamentous fungi such as Aspergillus niger, Aspergillus oryzae, and Trichoderma reesei are able to produce and secrete large concentrations of enzymes (e.g. amylases, proteases, cellulases) into the environment. Increasingly, these species and a few others are being used to produce recombinant proteins, particularly proteins of fungal origin (Table 1). For producing recombinant proteins (which may be a protein which the host organism already makes, i.e. an homologous protein, or a new, i.e. heterologous, protein), filamentous fungi offer the advantages of possessing an efficient secretion system, being able to glycosylate proteins and having higher specific growth rates than plant, insect or mammalian cells. Although the filamentous growth form causes more difficulties for mixing and aeration than does the unicellular growth form of yeast and bacteria, efficient fermentation technologies have been developed for antibiotic, organic acid and native enzyme production from filamentous fungi.