Phylogenetic diversity of culturable fungi from the deep-sea sediments of the Central Indian Basin and their growth characteristics

摘要

Very few studies have addressed the diversity of culturable fungi from deep-sea sediments. We are reporting here the diversity of culturable fungi in deep-sea sediments of the Central Indian Basin obtained from a depth of –5,000 m. A total of 16 filamentous fungi and 12 yeasts isolated from 20 sediment cores of –35 cm length were identified by 18S and ITS sequencing of SSU rDNA. Most of the filamentous fungi were Ascomycota, while two were Basidiomycota. Micro-scopic identification of sporulating cultures mostly matched either with 18S or ITS sequences but seldom with both the sequences. Phylogenetic analysis of ascomycetes using 18S sequence data grouped them into 7 clusters belonging to Aspergillus sp., Sagenomella sp., Exophiala sp., Capronia sp., Cladosporium sp., Acremonium sp. and Tritirachium sp. ITS sequence data grouped isolates into 6 clusters belonging to Aspergillus sp., uncultured member of Hypocreaceae, Exophiala sp., uncultured soil fungus, Hypocreales and Trichothecium sp. The two basidiomycete isolates were a Tilletiopsis sp. evident from 18S as well as ITS sequence data. In contrast, most of the yeast isolates belonged to Basidiomycota and only one isolate belonged to the phylum Ascomycota. Sequences of 18S as well as ITS gave matching identification of most of the yeasts. Filamentous fungi as well as the yeasts grew at 200 bar/5°C indicating their adaptations to deep-sea conditions. This is the first report on isolation of Sagenomella, Exophiala, Capronia and Tilletiopsis spp. from deep-sea sediments. This study reports on the presence of terrestrial fungi as a component of culturable fungi in deep-sea sediments.