Gaëtan Burgaud

We report the draft genome sequence of SR50, the first cultivated member of the genus JdFR-22 within the Archaeoglobaceae family, which currently includes three genera with cultivated representatives. Isolated from a shallow hydrothermal vent off Saint-Paul Island, a strictly protected area, SR50 is able to grow lithoautotrophically by sulfate reduction.

This study examines the fungal and fungal‐like stramenopile communities along the land‐to‐sea continuum to explore microbial connectivity across terrestrial and marine ecosystems. In addition to providing new ecological knowledge on coastal communities, the objectives were to assess the presence of terrestrial fungi and evaluate their potential as bioindicators of riverine influence on marine environments. Conducted in New Caledonia (southwest Pacific), the research involved 113 marine samples (water and sediment) and 148 additional soil samples from tropical/subtropical Pacific regions. Sampling spanned spatial and temporal gradients, including dry periods and a post‐cyclone runoff event. We used high‐throughput long‐read amplicon sequencing of the full‐length ITS rRNA gene, complemented by inference of fungal ecological traits from genus‐level annotations. In total, 1653 fungal OTUs were identified in marine samples, with distinct communities in sediment and water. Terrestrial fungal taxa were also detected in marine environments, with 306 genera exhibiting varying occurrence across sample types and periods. The cyclone runoff temporarily increased the richness of terrestrial fungal taxa by up to threefold, underscoring the impact of extreme events on marine coastal assemblages. Overall, this work provides the first study of fungal communities along New Caledonia's coastlines, highlighting fungal dispersal as a key component of land‐to‐sea connectivity.

Sulfation plays a critical role in the biosynthesis of small molecules, regulatory mechanisms such as hormone signaling, and detoxification processes (phase II enzymes). The sulfation reaction is catalyzed by a broad family of enzymes known as sulfotransferases (SULTs), which have been extensively studied in animals due to their medical importance, but also in plant key processes. Despite the identification of some sulfated metabolites in fungi, the mechanisms underlying fungal sulfation remain largely unknown. To address this knowledge gap, we conducted a comprehensive search of available genomes, resulting in the identification of 174 putative SULT genes in the Ascomycota phylum. Phylogenetic analysis and structural modeling revealed that these SULTs belong to the aryl sulfotransferase family, and they are divided into two potential distinct clusters of PAPS-dependent SULTs within the fungal kingdom. SULT genes from two marine fungi isolated from deep-sea hydrothermal vents, Hortaea werneckii UBOCC-A-208029 (HwSULT) and Aspergillus sydowii UBOCC-A-108050 SULT (AsSULT), were selected as representatives of each cluster. Recombinant proteins were expressed in Escherichia coli and biochemically characterized. HwSULT demonstrated high and versatile activity, while AsSULT appeared more substrate-specific. Here, HwSULT was used to sulfate the mycotoxin zearalenone, enhancing its cytotoxicity toward healthy feline intestinal cells.

Environmental pollution resulting from the accumulation of plastic waste poses a major ecological challenge. Biodegradation of these polymers relies on microorganisms capable of decomposing them, generally through the biodeterioration, biofragmentation, assimilation, and mineralization stages. This study evaluates the contribution and efficacy of indigenous soil yeasts isolated from a northeastern Algerian landfill in degrading low-density polyethylene (LDPE) plastic bag films. Candida tropicalis SLNEA04 and Rhodotorula mucilaginosa SLNEA05 were identified through internal transcribed spacer (ITS) and large subunit ribosomal RNA gene sequencing. These isolates were then tested for their ability to biodegrade LDPE films and utilized as the sole carbon source in vitro in a mineral salt medium (MSM). The biodegradation effect was examined using scanning electron microscopy (SEM), attenuated total reflectance–Fourier transform infrared (ATR-FTIR) spectroscopy, and X-ray diffraction (XRD). After 30 days of incubation at 25 °C, a significant weight loss was observed compared to the control for both cultures: 7.60% and 5.53% for C. tropicalis and R. mucilaginosa, respectively. SEM analysis revealed morphological alterations, including cracks and holes, ATR-FTIR detected new functional groups (alcohols, alkynes, aldehydes, alkenes and ketones), while XRD identified changes in the polymer crystallinity and phase composition. These findings underscore the potential of the two yeast isolates in LDPE biodegradation, offering promising insights for future environmental applications.

Two new fusarochromanone derivatives, deacetylfusarochromene (1) and deacetamidofusarochrom-2′,3-diene (2), along with the previously reported metabolites fusarochromanone TDP-2 (3), fusarochromene (4), 2,2-dimethyl-5-amino-6-(2′E-ene-4′-hydroxylbutyryl)-4-chromone (5), fusarochromanone (6), (−)-chrysogine (7), and equisetin (8), were isolated from the marine fungus Fusarium equiseti UBOCC-A-117302. The structures of the compounds were determined by extensive spectrometric (HRMS) and spectroscopic (1D and 2D NMR) analyses, as well as specific rotation. Among them, 2 and 5 showed inhibition of three protein kinases with IC₅₀ values ranging from 1.42 to 25.48 μM. Cytotoxicity and antimicrobial activity of all isolated compounds were also evaluated. Six fusarochromanone derivatives (1–6) exhibited diverse activities against three cell lines, RPE-1, HCT-116, and U2OS (IC₅₀ values ranging from 0.058 to 84.380 μM). Equisetin (8) showed bactericidal activities against Bacillus cereus and Listeria monocytogenes (MBC values of 7.8 and 31.25 µM, respectively), and bacteriostatic activity against Enterococcus faecalis (MIC value of 31.25 µM). Compounds 2 and 4 showed bacteriostatic activities against Listeria monocytogenes (MIC of 125 µM).

Plastic pollution of the ocean is a major environmental threat. In this context, a better understanding of the microorganisms able to colonize and potentially degrade these pollutants is of interest. This study explores the colonization and biodegradation potential of fungal communities on foamed polystyrene and alternatives biodegradable plastics immersed in a marina environment over time, using the Brest marina (France) as a model site. The methodology involved a combination of high-throughput 18S rRNA gene amplicon sequencing to investigate fungal taxa associated with plastics compared to the surrounding seawater, and a culture-dependent approach to isolate environmentally relevant fungi to further assess their capabilities to utilize polymers as carbon sources. Metabarcoding results highlighted the significant diversity of fungal communities associated with both foamed polystyrene and biodegradable plastics, revealing a dynamic colonization process influenced by the type of polymer and immersion time. Notably, the research suggests a potential for certain fungal species to utilize polymers as a carbon source, emphasizing the need for further exploration of fungal biodegradation potential and mechanisms.

Intertidal zones comprise diverse habitats and directly suffer from the influences of human activities. Nevertheless, the seasonal fluctuations in fungal diversity and community structure in these areas are not well comprehended. To address this gap, samples of seawater and sediment were collected seasonally from the estuary and swimming beaches of Qingdao’s intertidal areas in China and were analyzed using a metabarcoding approach targeting ITS2 rDNA regions. Compared to the seawater community dominated by Ciliophora and Agaricomycetes, the sediment community was rather dominated by Dothideomycetes and Eurotiomycetes. Furthermore, the seawater community shifted with the seasons but not with the locations, while the sediment community shifted seasonally and spatially, with a specific trend showing that Cladosporium, Alternaria, and Aureobasidium occurred predominantly in the estuarine habitats during winter and in the beach habitats during spring. These spatiotemporal shifts in fungal communities’ composition were supported by the PERMANOVA test and could be explained partially by the environmental variables checked, including temperature, salinity, and total organic carbon. Unexpectedly, the lowest fungal richness was observed in the summer sediments from two swimming beaches which were attracting a high influx of tourists during summer, leading to a significant anthropogenic influence. Predicted trophic modes of fungal taxa exhibited a seasonal pattern with an abundance of saprotrophic fungi in the summer sediments, positively correlating to the temperature, while the taxa affiliated with symbiotroph and pathotroph-saprotroph occurred abundantly in the winter and spring sediments, respectively. Our results demonstrate the space–time shifts in terms of the fungal community, as well as the trophic modes in the intertidal region, providing in-depth insights into the potential influence of environmental factors and human activity on intertidal mycobiomes.

Early research on marine fungi was mostly descriptive, with an emphasis on their diversity and taxonomy, especially of those collected at rocky shores on seaweeds and driftwood. Subsequently, further substrata (e.g. salt marsh grasses, marine animals, seagrasses, sea foam, seawater, sediment) and habitats (coral reefs, deep-sea, hydrothermal vents, mangroves, sandy beaches, salt marshes) were explored for marine fungi. In parallel, research areas have broadened from micro-morphology to ultrastructure, ecophysiology, molecular phylogenetics, biogeography, biodeterioration, biodegradation, bioprospecting, genomics, proteomics, transcriptomics and metabolomics. Although marine fungi only constitute a small fraction of the global mycota, new species of marine fungi continue to be described from new hosts/substrata of unexplored locations/habitats, and novel bioactive metabolites have been discovered in the last two decades, warranting a greater collaborative research effort. Marine fungi of Africa, the Americas and Australasia are under-explored, while marine Chytridiomycota and allied taxa, fungi associated with marine animals, the functional roles of fungi in the sea, and the impacts of climate change on marine fungi are some of the topics needing more attention. In this article, currently active marine mycologists from different countries have written on the history and current state of marine fungal research in individual countries highlighting their strength in the subject, and this represents a first step towards a collaborative inter- and transdisciplinary research strategy.