Fungal diversity in deep-sea extreme environments

The deep-sea is one of the most mysterious and unexplored extreme environments, holding great potential and interest for science. Despite extensive studies on deep-sea prokaryotes, the diversity of fungi, one of the most ecologically important groups of eukaryotic micro-organisms, remains largely unknown. However, the presence of fungi in these ecosystems is starting to be recognised. Many fungi have been isolated by culture-dependent methods from various deep-sea environments, with the majority showing similarity to terrestrial species. However, culture-independent methods have revealed many novel fungal phylotypes, including novel fungal lineages recently described as Cryptomycota, which are suspected to lack typical fungal chitin-rich cell walls. Although true fungal diversity and its role in deep-sea environments is still unclear, the intention of this review is to assess current knowledge of the diversity of fungi in these ecosystems and to suggest future direction for deep-sea fungal research.

► The presence of fungi in deep-sea ecosystems is starting to be recognised.
► Many cultured fungi from deep-sea show similarity to terrestrial species.
► Culture-independent methods have revealed novel fungal phylotypes in deep-sea.
► The dominant presence of zoosporic fungi in deep-sea environments has been reported.
► Deep-sea fungi may provide key insights into the evolutionary history of fungi.