Ribosomal RNA internal transcribed spacer-1 (ITS1) metabarcoding was used to investigate the distribution patterns of fungal communities and the factors influencing these patterns in subtropical Chinese seas, including the southern and northern Yellow Sea and the Bohai Sea. These seas were found to harbor high levels of fungal diversity, with 816 operational taxonomic units (OTUs) that span 130 known genera, 36 orders, 14 classes and 5 phyla. Ascomycota was the most abundant phylum, containing 72.18% and 79.61% of all OTUs and sequences, respectively, followed by Basidiomycota (19.98%, 18.64%), Zygomycota (1.10%, 0.11%), Chytridiomycota (0.25%, 0.04%) and Rozellomycota (0.12%, 0.006%). The compositions of fungal communities across these three sea regions were found to be vary, which may be attributed to sediment source, geographical distance, latitude and some environmental factors such as the temperature and salinity of bottom water, water depth, total nitrogen, and the ratio of total organic carbon to nitrogen. Among these environmental factors, the temperature of bottom water is the most important driver that governs the distribution patterns of fungal communities across the sampled seas. Our data also suggest that the cold-water mass of the Yellow Sea likely balances competitive relationships between fungal taxa rather than increasing species richness levels.

Considerable attention has been paid to marine derived endophytic fungi, owing to their capacity to produce novel secondary metabolites with potent bioactivities. In this study, two new compounds with a prenylated diphenyl ether structure—diorcinol L (1) and (R)-diorcinol B (2)—were isolated from the marine algal-derived endophytic fungus Aspergillus tennesseensis, along with seven known compounds: (S)-diorcinol B (3), 9-acetyldiorcinol B (4), diorcinol C (5), diorcinol D (6), diorcinol E (7), diorcinol J (8), and a dihydrobenzofuran derivative 9. Their structures were elucidated by extensive NMR spectroscopy studies. Compound 2 represents the first example of an R-configuration in the prenylated moiety. All these isolated compounds were examined for antimicrobial and cytotoxic activities. Compounds 1–9 exhibited antimicrobial activities against some human- and plant-pathogenic microbes with MIC values ranging from 2 to 64 μg/mL. Moreover, compound 9 displayed considerable inhibitory activity against the THP-1 cell line in vitro, with an IC₅₀ value of 7.0 μg/mL.

The intertidal region is one of the most dynamic environments in the biosphere, which potentially supports vast biodiversity. Fungi have been found to play important roles in marine ecosystems, e.g. as parasites or symbionts of plants and animals, and as decomposers of organic material. The fungal diversity in intertidal region, however, remains poorly understood. In this study, sediment samples from various intertidal habitats of Chinese seas were collected and investigated for determination of fungal community and spatial distribution. Through ribosomal RNA internal transcribed spacer-2 (ITS2) metabarcoding, a high-level fungal diversity was revealed, as represented by 6,013 OTUs that spanned six phyla, 23 classes, 84 orders and 526 genera. The presence of typical decomposers (e.g. Corollospora in Ascomycota and Lepiota in Basidiomycota) and pathogens (e.g. Olpidium in Chytriomycota, Actinomucor in Zygomycota and unidentified Rozellomycota spp.), and even mycorrhizal fungi (e.g. Glomus in Glomeromycota) indicated a complicated origin of intertidal fungi. Interestingly, a small proportion of sequences were classified to obligate marine fungi (e.g. Corollospora, Lignincola, Remispora, Sigmoidea). Our data also showed that the East China Sea significantly differed from other regions in terms of species richness and community composition, indicating a profound effect of the huge discharge of the Yangtze River. No difference in fungal communities was detected, however, among habitat types (i.e. aquaculture, dock, plant, river mouth and tourism). These observations raise further questions on adaptation of these members to environments and the ecological functions they probably perform.

To identify Cladosporium-like isolates associated with marine algae, phylogenetic analyses were conducted using a combined data set of the nuc rDNA internal transcribed spacer (ITS) region (ITS1-5.8S-ITS2 = ITS), 28S gene, and partial RNA polymerase II second largest subunit (RPB2). These isolates were confirmed as belonging to Neodevriesia (Neodevriesiaceae), a genus recently segregated from Cladosporium. Two new species, Neodevriesia cladophorae and N. grateloupiae, are described on the basis of morphological and phylogenetic distinctions, and this is the first report of Neodevriesia species from the marine environment. Devriesia fici, D. fraserae, and D. sardiniae are transferred to Neodevriesia based on the phylogenetic affinities and morphological characters of their ex-type specimens.