Welcome to IMC 2018 International Mycological Congress
Microscopic fungi from the ocean: their concept, diversity and future in Mexico in a globalized world
- M. González
- R. Hanlin
The marine fungal biology is a subdiscipline of Mycology that studies the microscopic fungi that inhabit the ocean, from an ecological perspective. This group of marine microorganisms is classified in the Kingdom Fungi, one of the largest and most diverse of all of the eukaryotic organisms that includes a non-taxonomic group called –microscopic fungi/micromycetes– which develops fungal structures of microscopic size during their whole life cycles. The micromycetes form part of all ecosystems, continental or oceanic, where they perform an endless variety of key ecological functions as saprotrophs, degrading organic remains for nutrient recycling, or symbiotrophs associated with microscopic or macroscopic eukaryotes from other kingdoms. The fungal microorganisms synthesize biochemicals as a result of their complex and diverse metabolic pathways essential to the ecosystems they inhabit. The concept of marine fungi has changed in accordance with advances in science. At present it is defined as ‘any fungus that is recovered repeatedly from marine habitats because: 1) It is able to grow and/or sporulate in marine environments; 2) It forms symbiotic relationships with other marine organisms; 3) It is shown to adapt and evolve at the genetic level or be metabolically active in marine environments’ and in addition, 4) they exhibit adaptations necessary in order to live in the oceans that are manifested through the possession of specific morphological characters. The fungal diversity that inhabits the planet remains mainly unknown. At present, only 2% of the total number of fungi is described and the majority of species are from terrestrial ecosystems. Of over 100,000 fungi known worldwide, only 1,112 are marine. The ocean covers 71 percent of Earth and 95% is underwater and unexplored. The possibility that the oceans hold a larger and exclusive fungal diversity than that registered from the continents emphasizes the need to describe the fungi from innumerable marine habitats that range from coastal to open sea regions, including those most adverse to the eukaryotic life style. Mexico is ranked as one of the five megadiverse countries of the world. Overall, not more than 100 species have been recorded from its marine ecoregions. The distinctive ecological characteristics of each Mexican marine ecosystem could result in the presence of a new and/or endemic mycobiota in this country with high applied value. Many potentially useful metabolites from undescribed fungi wait to be discovered. Strategies are then proposed in order to obtain the marine fungi diversity from these valuable ecosystems to isolate and identify the species. The establishment of taxonomic identification training programs with the goal of increased use of traditional methods to obtain and conserve cultures of Mexican microscopic marine fungi are necessary to investigate their potential biotechnological use. Therefore, in order for marine mycology to advance in this era that confronts global, environmental and social challenges, it is required to follow a strategy that integrates taxonomic/phylogenetic, genetic/genomic and ecological/functional aspects. To this end, the mycologists of the future need to possess abilities that permit them to attain high levels of innovation, collaboration and operation of cutting-edge technology.
New lineages in the Pezizomycotina from marine ascomycetes described from Thailand
- S. Preedanon
- A. Klaysuban
- S. Suetrong
- W. Promchoo
- W. Gundool
- T. Sangtiean
- P. Kedkaew
- J. Sakayaroj
Thailand is a biodiversity rich country; however, only 34% of marine fungi have been documented compared to the figures worldwide. To complement the sporadic knowledge on marine fungi in Thailand, we therefore are developing a baseline research in marine fungi to encourage awareness on the conservation of bioresources in the marine protected areas in the country. Noteworthy lignicolous ascomycetous species were collected from southern Thailand. Firstly, a new marine Sordariomycete, Lautospora obovoidiella sp. nov., was found on decaying intertidal mangrove wood, and is characterized by having immersed ellipsoidal ascomata, unitunicate cylindrical asci, obovoid and thickened-wall ascospore. Its morphological features are similar to L. simillima and L. gigantea, but differ in ascospore shape in possessing a round apical region and elongate basal part of ascospore. Based on our molecular study, L. obovoidiella sp. nov. forms a well-supported clade with the other Lautospora species within the Lautosporaceae in the Sordariomycetes. Additionally, strains of L. obovoidiella sp. nov. constitute a separate group within the Lautospora species subclade with strong statistical supports. Interestingly, the Lautosporaceae forms a highly supported monophyletic clade without any named orders in the Sordariomycetes. Therefore, a potential new order, Lautosporales, is proposed. Secondly, a novel Dothideomycetes species, Helicascus satunensis sp. nov., was investigated on nypa palm fruit; its markedly morphological character possesses semi-immersed lenticular ascomata, multi-locules; bitunicate ascus; smooth, dark-brown ascospores, obovoid, 1-septate and unequally 2-celled. Based on molecular phylogenetic evidence, H. satunensis sp. nov. formed a well-supported clade within Helicascus species and closely related with marine species within the Morosphaeriaceae, order Pleosporales. Consequently, the genus Helicascus formed a distinct clade from the genus Morosphaeria. Therefore, with the unique morphological and molecular characteristics, a new family Helicascaceae is suggested for Helicascus species. In conclusion, this study gives an insight into the distribution and diversity of marine fungi present in Thai mangroves especially in the southern coast. Currently 184 marine fungal species were recorded for Thailand.
Deep-sea microfungal degradation of hydrocarbons: implications for oil spill bioremediation
- P. Vélez Aguilar
- M. Riquelme
The Gulf of Mexico basin is a biodiverse and productive environment that provides a wide array of resources. In addition, petroleum exploitation within this area sustains a multi-millionaire industry. However, on numerous occasions these operations have resulted in major environmental disasters of unknown consequences. Nonetheless, the estimation of ecological costs of oil spills on marine ecosystems is limited to the extent of our knowledge on the autochthonous biota and its functional capacities.Fungi are involved in key ecological deep-sea processes, yet these microorganisms have been rarely cultured and preserved from deep-sea samples. Moreover these microorganisms have been recognized as a characteristic component of post-spill deep-sea communities in sediments. So, the objectives of this work were to analyze cultivable fungal diversity from deep-sea sediment samples from two major oil-drilling sites in the Gulf of Mexico for their response to hexadecane and 1-hexadecene as sole carbon sources, and to evaluate their gene expression profiles in response to the utilization of these hydrocarbons. Deep-sea sediment samples were collected during the Metagenómica-Malla Finacruise, as part of the Consorcio de Investigación del Golfo de México (CIGoM) agenda. Fungal isolates were obtained and identified based on the evaluation of sequence data from the nuclear ribosomal internal transcribed spacer including the 5.8 rDNA region. Isolates were screened for their sensitivity to hydrocarbons, and tolerant OTUs were grown with hexadecane and 1-hexadecene as sole carbon sources to test their ability to break down these long-chain aliphatic hydrocarbons in liquid culture. A differential transcriptome analysis was performed for selected OTUs to evaluate genetic signatures during hydrocarbon utilization. We obtained 25 isolates, which clustered into 7 OTUs, that showed differential sensitivity profiles towards hydrocarbons. Our results agree with previous work on deep-sea fungi reporting low levels of cultivable diversity, with Ascomycota as the dominant phylum. Moreover, six of these taxa proved to metabolize the tested alkane and alkene as sole carbon sources, confirming deep-sea fungal taxa as valuable genetic resources for hydrocarbon bioremediation. Transcriptome data on selected deep-sea fungal isolates revealed differential gene expression between treatments. This work provides the first insights of cultivable fungal diversity from deep-sea sediments in the Gulf of Mexico, and their response to hexadecane and 1-hexadecene inputs, shedding light on a better understanding of the deep-sea ecosystem dynamics and bioremediation using deep-sea native taxa.
Marine fungi (sensu stricto) – an underexplored resource of natural products
- D. Overy
Marine fungi in the strict sense (sensu stricto) remain one of the few underexplored resources of natural products and are a proven source of bioactive and structurally diverse molecules. However reports of new chemistry from marine fungi sensu stricto are sparse; rather the literature is dominated by “marine-derived” isolates of well-known osmotolerant terrestrial genera. ‘Omics’-based investigations have shed some light on the role that abiotic/biotic factors play in the regulation of natural product production. Culture conditions are likely responsible for many of the reports of new chemistry from osmotolerant species. Osmotolerant terrestrial isolates under saline stress have been found to produce identical chemistry to previous reports from marine-derived counterparts. To truly explore marine fungi as a source of new natural products, new isolation strategies need to be adopted by natural products chemists as culture isolates remain the primary source from which these scientists discover and obtain new molecules. To refocus efforts away from common “marine-derived” fungi, recommendations will be presented on modern isolation and fermentation techniques used to isolate truly unique linages of marine fungi and to maximize their natural product production.
Arctic marine fungi, their diversity and bioactivity
- T. Rämä
The Arctic Ocean and its adjacent seas are one of the least studied geographical areas in marine mycology. Despite the stressful environment and harsh climatic conditions, numerous marine fungi have evolved mechanisms to survive and function in the Arctic, making them intriguing study objects for basic and applied research. The aim of ongoing efforts is to characterize the richness and diversity of Arctic marine mycobiomes and get insights into the ecology of fungal communities in different substrates. The diversity research has focused on driftwood- and macroalga-associated fungi, using culturing and culture-independent high-throughput sequencing (HTS), as well as morphological examination of fruiting structures. Sampling has been conducted in onshore and offshore locations up to 82 degrees north. The research has revealed a greater than expected species richness. In total, 100 species of filamentous fungi have been morphologically documented from the Arctic, whereas molecular data provide evidence for a far greater diversity consisting of hundreds of operational taxonomic units (OTUs; defined using 97% ITS similarity as threshold) in single substrates. For example, fifty pieces of driftwood studied using culturing combined with Sanger sequencing of pure cultures and a HTS approach, revealed a richness of almost 1000 OTUs, whereas the total richness was extrapolated to be 1500 OTUs. Interestingly, several OTUs showed a significant detection bias for culturing and against the HTS approach. Some groups of fungi, such as the Leotiomycetes and the strictly marine order Lulworthiales, seem to host high richness in Arctic driftwood and macroalgae, including undescribed species. The established culture collection consisting of approximately 1000 fungal isolates has been used for marine fungal bioprospecting. Fungal extracts produced in monocultures as well as in co-cultures with bacteria have been screened for bioactivity, and active extracts subjected to bioassay-guided isolation of active molecules. Co-culturing marine fungi with bacteria has led to increased antibacterial activity, and resulted in the identification of novel compounds. Arctic marine fungi are counted in thousands, seem to play active ecological roles in their native environment and produce novel bioactive molecules laying ground for a fruitful biodiscovery work.
Fungi from Fundy: Biodiversity of intertidal fungi from megatidal Nova Scotia, Canada
- A. Walker
- S. Adams
- V. Taylor
- T. D'Entremont
- D. Divanli
- B. Landry
- B. Robicheau
The fungal diversity of Nova Scotian's saltmarshes and the megatidal marine environments of the Bay of Fundy is underexplored. Fungi are key decomposers and saltmarsh plant root symbionts in these systems. We are expanding our knowledge of the marine fungal diversity from Nova Scotia and determining which of the fungi present have potential use in marine oil spill remediation and saltmarsh restoration. Collections of seawater, marine sediments and saltmarsh and algal detritus floating in sea water have been taken since the summer of 2015 from sites including Apple River, Kingsport, and Bon Portage Island, Nova Scotia. Samples were placed onto saltwater media (saltwater potato dextrose agar, and saltwater agar containing antibiotics) selective for marine fungi. Detrital marine wood and plant samples were incubated in sterile damp chambers to promote the emergence of fungal reproductive structures used for microscopic identification and single spore isolations. ITS rDNA barcode sequences were identified from axenic cultures using the online reference sequence database NCBI Genbank. From 11 locations sampled in Nova Scotia, 101 fungi were identified from marine habitats and two have been confirmed as new fungal species. We present morphological and multi-locus molecular evidence for a new species of obligate lignicolous marine fungus in the genus Lulworthia (Luworthiales, Sordariomycetes, Ascomycota) isolated from naturally occurring submerged wood at Apple River Bay, Cumberland County, Nova Scotia.