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

Abstract

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. Microscopic 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.

Living strategy of cold-adapted fungi with the reference to several representative species

“…Fungi isolated from deep seas were first reported nearly 50 years ago (Roth et al 1964), then a great number of fungi including some novel species have been published by both conventional culture-dependent (Raghukumar et al 2004; Gadanho and Sampaio 2005; Damare et al 2006; Nagahama et al 2006; Le Calvez et al 2009; Singh et al 2010) and culture-independent methods (Lai et al 2007; Le Calvez et al 2009; Nagano et al 2010). Le Calvez et al (2009) reported striking differences in their comparison of deep-sea fungal diversity assessed by culture-dependent and culture-independent methods.…”

Fungal diversity of marine biofilms on artificial reefs in the north-central Gulf of Mexico

“…Our characterization of artificial reef fungal biofilm communities represents the first step towards understanding the fungal component of microbial diversity of hard substrata within the MS Sound, an economically productive estuary for fisheries including shellfish. Considering the increasing number of reports on the occurrence of marine fungi and their involvement in detrital processing, it can be concluded that the current microbial loop model neglects the role of fungi in the processing of organic matter in marine environments (Hyde et al 1998, Singh et al 2010, Gutiérrez et al 2011, Mouton et al 2012). Further research is needed to determine fungal roles in marine ecological processes in hopes of providing a more complete model of organic material degradation in coastal ecosystems, foundational to food webs and nutrient cycling (Gutiérrez et al 2011, Mouton et al 2012.…”

Culturable halotolerant fungal isolates from Southern California Gulf sediments

“…To isolate micromycetes from marine sediments, different culture conditions have been tested such as agar types, atmospheric pressure (1-1200 bars), temperatures (5°C or 30 °C) and light or darkness (Roth et al 1964;Damare et al 2006;Singh et al 2010;Singh et al 2012). A greater number of fungi being isolated has been achieved using MEA (Malt Extract Agar) diluted to 1:5, 200 bar and 5°C.…”

“…In this study we used YEPD agar at 100% concentration, and darkness, as these conditions were favorable for the isolation of micromycetes from marine sediments in comparison to other works. Singh et al (2010) reported 28 micromycetes from 496 sediments, while Damare et al (2006) isolated 181 micromycetes from 672 sediments. All these studies were carried out in the central basin of India by Roth et al (1964) and Singh et al (2010) suggest that the difference in the frequency of micromycetes recovery may be due to the oceanographic conditions where the sediments were collected.…”

“…Singh et al (2010) reported 28 micromycetes from 496 sediments, while Damare et al (2006) isolated 181 micromycetes from 672 sediments. All these studies were carried out in the central basin of India by Roth et al (1964) and Singh et al (2010) suggest that the difference in the frequency of micromycetes recovery may be due to the oceanographic conditions where the sediments were collected. In this study we observed that agar nutrients affect the isolation frequency as did the antibiotic, darkness and temperature, since we tested MEA, light, temperatures (25-37ºC) and ampicillin as antibiotic.…”