The culturable mycobiota associated with three Atlantic sponges, including two new species: Thelebolus balaustiformis and T. spongiae

Abstract

Covering 70 % of Earth, oceans are at the same time the most common and the environment least studied by microbiologists. Considering the large gaps in our knowledge on the presence of marine fungi in the oceans, the aim of this research was to isolate and identify the culturable fungal community within three species of sponges, namely Dysidea fragilis, Pachymatisma johnstonia and Sycon ciliatum, collected in the Atlantic Ocean and never studied for their associated mycobiota. Applying different isolation methods, incubation temperatures and media, and attempting to mimic the marine and sponge environments, were fundamental to increase the number of cultivable taxa. Fungi were identified using a polyphasic approach, by means of morpho-physiological, molecular and phylogenetic techniques. The sponges revealed an astonishing fungal diversity represented by 87 fungal taxa. Each sponge hosted a specific fungal community with more than half of the associated fungi being exclusive of each invertebrate. Several species isolated and identified in this work, already known in terrestrial environment, were first reported in marine ecosystems (21 species) and in association with sponges (49 species), including the two new species Thelebolus balaustiformis and Thelebolus spongiae, demonstrating that oceans are an untapped source of biodiversity.

Fungi in the Marine Environment: Open Questions and Unsolved Problems

“…With respect to model marine fungal hosts, there has been success with studying fungi associated with marine sponges and corals using both culture-based (34, 35) and culture-independent (37, 55) techniques. Recent studies have reported new fungal species from sponges (114) and examined how environmental factors impact fungal communities in coral hosts (37, 57, 115). Other potential fungal models that are in various stages of development include several in the Ascomycota, including Phaeotheca salicorniae, Knufia petricola, and Hortaea werneckii (A. Gladfelter et al ., unpublished data), and multiple ongoing genome sequencing projects of marine fungi via the 1000 Fungal Genomes Project at the Department of Energy’s Joint Genome Institute.…”

Fungal Diversity in the Neptune Forest: Comparison of the Mycobiota of Posidonia oceanica, Flabellia petiolata, and Padina pavonica

“…However, whether the macro-organisms, their microbiota, or the holobiont derived from their strict interaction is responsible for the production of the active compounds is still unclear. With the exclusion of cosmopolitan and/or widespread fungi, we can hypothesize the shaping of a relation between the microorganisms and their host, as recently demonstrated for three Atlantic sponges (Bovio et al, 2018). The establishment of a holobiont depends on both active (selection) and passive (drift) events.…”

“…Indeed, they have been retrieved worldwide from biotic and abiotic substrates such as algae, sediments, invertebrates, drift wood, etc. (Jones and Pang, 2012;Garzoli et al, 2014Garzoli et al, , 2015Garzoli et al, , 2018Gnavi et al, 2017;Raghukumar, 2017;Bovio et al, 2018). Nevertheless, despite the total fungal diversity has been estimated to range between 10,000 and 12,500 taxa (Jones et al, 2019), only 1281 species have been described to date 1 .…”

News from the Sea: A New Genus and Seven New Species in the Pleosporalean Families Roussoellaceae and Thyridariaceae

“…In recent surveys aimed to uncover the underwater fungal diversity, 19 unidentified Roussoellaceae were isolated from several substrates, as follows: 12 from the brown alga Padina pavonica (L.) Thivy [10], 4 from the green alga Flabellia petiolata (Turra) Nizamuddin [11], 2 from the seagrass Posidonia oceanica (L.) [12] Delile, and 1 from the Atlantic sponge Dysidea fragilis (Montagu) [13]. The Roussoellaceae is a well-resolved family in the Pleosporales [14].…”