title: Yeast forms dominate fungal diversity in the deep oceans.
abstract: Fungi are the principal degraders of biomass in most terrestrial ecosystems. In contrast to surface environments, deep-sea environmental gene libraries have suggested that fungi are rare and non-diverse in high-pressure marine environments. Here, we report the diversity of fungi from 11 deep-sea samples from around the world representing depths from 1,500 to 4,000 m (146-388 atm) and two shallower water column samples (250 and 500m). We sequenced 239 clones from 10 fungal-specific 18S rRNA gene libraries constructed from these samples, from which we detected only 18 fungal 18S-types in deep-sea samples. Our phylogenetic analyses show that a total of only 32 fungal 18S-types have so far been recovered from deep-sea habitats, and our results suggest that fungi, in general, are relatively rare in the deep-sea habitats we sampled. The fungal diversity detected suggests that deep-sea environments host an evolutionarily diverse array of fungi dominated by groups of distantly related yeasts, although four putative filamentous fungal 18S-types were detected. The majority of our new sequences branch close to known fungi found in surface environments. This pattern contradicts the proposal that deep-sea and hydrothermal vent habitats represent ancient ecosystems, and demonstrates a history of frequent dispersal between terrestrial and deep-sea habitats.
authors.affiliation: Department of Zoology, University of Oxford, The Tinbergen Building, South Parks Road, Oxford OX1 3PS, UK.
authors.forename: David
authors.initials: D
authors.lastname: Bass
authors.forename: Alexis
authors.initials: A
authors.lastname: Howe
authors.forename: Nick
authors.initials: N
authors.lastname: Brown
authors.forename: Hannah
authors.initials: H
authors.lastname: Barton
authors.forename: Maria
authors.initials: M
authors.lastname: Demidova
authors.forename: Harlan
authors.initials: H
authors.lastname: Michelle
authors.forename: Lily
authors.initials: L
authors.lastname: Li
authors.forename: Holly
authors.initials: H
authors.lastname: Sanders
authors.forename: Sarah C
authors.initials: SC
authors.lastname: Watkinson
authors.forename: Simon
authors.initials: S
authors.lastname: Willcock
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Richards
mesh_terms: D044822:Biodiversity; D019295:Computational Biology; D017753:Ecosystem; D005658:Fungi / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D015723:Gene Library; D009792:Oceans and Seas; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D012623:Seawater / Q000382:microbiology*
chemical_list: D012337:RNA, Ribosomal, 18S