Unravelling the hidden diversity of cave mycobiota in Thailand's Satun Geopark.

Karst caves are distinctive ecosystems that have limited nutrients, darkness, low to moderate temperatures, and high moisture levels, which allow for a diverse range of fungal communities to thrive. Despite their significance, little is understood about the fungi found in karst caves in Thailand. In 2019, we studied the cultured mycobiota from five substrate types (air, water, rock, soil/sediment, and organic debris) in two karst caves (Le Stegodon and Phu Pha Phet Caves) of the Satun UNESCO Global Geopark, southern Thailand. A cumulative count of 829 distinct fungal morphological types was identified, encompassing 319 fungal culturable were observed. Based on preliminary analyses of the internal transcribed spacer (ITS) sequence using BLAST searches, the most common phylum among the fungal morphotypes was Ascomycota, harboring 282 species in 91 genera, 93.4% of which were distributed in the classes Eurotiomycetes, Sordariomycetes, and Dothideomycetes. The most common fungal genera identified in the two karst caves were Aspergillus, Penicillium, Cladosporium, Talaromyces, Xylaria, and Trichoderma, with 45, 41, 24, 14, 14, and 6 species identified, respectively. Discovering fungi in Thai karst caves highlights the extensive fungal diversity in the Satun UNESCO Global Geopark, implying undiscovered species, and emphasizing the need for comprehensive investigations in other unexplored Thai karst caves.

Studies on the Genus Pyrenopolyporus (Hypoxylaceae) in Thailand Using a Polyphasic Taxonomic Approach.

Over the past two decades, hypoxylaceous specimens were collected from several sites in Thailand. In this study, we examined their affinity to the genus Pyrenopolyporus using macroscopic and microscopic morphological characters, dereplication of their stromatal secondary metabolites using ultrahigh performance liquid chromatography coupled to diode array detection and ion mobility tandem mass spectrometry (UHPLC-DAD-IM-MS/MS), and molecular phylogenetic analyses. We describe and illustrate five novel species and a new record for the country, present multi-locus phylogenetic analyses that show the distinction between the proposed species, and provide proteomic profiles of the fungi using matrix associated laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF/MS) for the first time. Based on our findings, this strategy is useful as a complementary tool to distinguish species between Daldinia and Pyrenopolyporus in a consistent way with the phylogenetic analysis.

Two Novel Species of Talaromyces Discovered in a Karst Cave in the Satun UNESCO Global Geopark of Southern Thailand.

Karst caves are oligotrophic environments that appear to support a high diversity of fungi. Studies of fungi in Thailand's caves are limited. During a 2019 exploration of the mycobiota associated with soil samples from a karst cave, namely, Phu Pha Phet in the Satun UNESCO Global Geopark in Satun Province, southern Thailand, two previously undescribed fungi belonging to Talaromyces (Trichocomaceae, Eurotiales, Eurotiomycetes) were studied using a polyphasic approach combining phenotypic and molecular data. Based on datasets of four loci (ITS, BenA, CaM, and RPB2), phylogenetic trees of the section Trachyspermi were constructed, and two new species-Talaromyces phuphaphetensis sp. nov. and T. satunensis sp. nov.-phylogenetically related to T. subericola, T. resinae, and T. brasiliensis, are described. Detailed descriptions and illustrations of the new species are provided. This study increases the number of cave-dwelling soil fungi discovered in Thailand's Satun UNESCO Global Geopark, which appears to be a unique environment with a high potential for discovering fungal species previously undescribed.

Cytotoxic hydroanthraquinones from the mangrove-derived fungus Paradictyoarthrinium diffractum BCC 8704.

Two new hydroanthraquinones, paradictyoarthrins A (1) and B (2), were isolated from the mangrove-derived fungus Paradictyoarthrinium diffractum BCC 8704. Structures of the new compounds were elucidated by analyses of the NMR spectroscopic and mass spectrometry data. The absolute configuration of 1 was determined by X-ray crystallography. These compounds exhibited cytotoxic activities.

Theissenia reconsidered, including molecular phylogeny of the type species T. pyrenocrata and a new genus Durotheca (Xylariaceae, Ascomycota).

The genus Durotheca is introduced with D. depressa sp. nov., as type. Hypoxylon comedens is transferred to Durotheca, based on its morphology with further evidence from molecular phylogenetic studies; a combined ß-tubulin and α-actin gene dataset. Theissenia cinerea is synonymized with D. comedens, and the type of Theissenia, T. pyrenocrata, is shown to occupy a basal, rather distant position in a monotypic clade in relation to sequenced taxa of Durotheca. This clade has an unresolved position in relation to the two informal subfamilies "Xylarioideae" and "Hypoxyloideae" within the Xylariaceae. New distributional data for D. comedens and T. pyrenocrata are presented, with the former found to be widespread in South-East Asia and the latter is reported as new from western Amazonia (Ecuador). One further species described in Theissenia, T. rogersii, is transferred to Durotheca, whilst T. eurima is accepted in Theissenia.

Ring B aromatic norpimarane glucoside from a Xylaria sp.

A novel 20-norpimarane glucoside, xylopimarane (1), together with the known sphaeropsidin C (2) and clonostachydiol (3), was isolated from the fungus Xylaria sp. BCC 4297. Compound 1 exhibited cytotoxicity to cancer cell lines KB, MCF-7, and NCI-H187 with respective IC(50) values of 1.0, 13, and 65 µM.

Lepraric acid derivatives as chemotaxonomic markers in Hypoxylon aeruginosum, Chlorostroma subcubisporum and C. cyaninum, sp. nov.

Hypoxylon aeruginosum (Xylariaceae), an infrequently encountered predominantly tropical pyrenomycete, of which two varieties are known to science, is characterised by having a cyan blue stromatal surface or subsurface. In the course of our ongoing chemotaxonomic evaluation of the Xylariaceae, specific profiles of H. aeruginosum were observed by high performance liquid chromatography, coupled with diode array detection and mass spectrometry (hplc-DAD/MS). By comparison with an authentic standard, lepraric acid and several yet unidentified metabolites with similar hplc-DAD/MS characteristics were detected in the stromata of the type material and other specimens of this species. Interestingly, lepraric acid was hitherto only known from lichenised ascomycetes. Hypoxylon aeruginosum, which is here reported first from Africa and Asia, contained none of the metabolites that were previously detected in other Xylariaceae, except for stromata growing hyperparasitically on other Hypoxylon species. A different lepraric acid derivative was also detected in the type specimen of Chlorostroma subcubisporum, which differs from H. aeruginosum by having a green stromatal surface, cuboid ascospores, and in lacking an amyloid ascal apical apparatus. A second species of Chlorostroma, which showed essentially the same metabolite profile as H. aeruginosum, is described from Thailand. We conclude that Chlorostroma and H. aeruginosum are closely related. However, no taxonomic conclusions are drawn from these findings because no cultures have so far become available to study their anamorphic morphology, their secondary metabolites in culture, and their molecular phylogeny. Taxonomic novelty: Chlorostroma cyaninum Læssøe, Srikitikulchai & J. Fournier, sp. nov.

Oblongolides from the endophytic fungus Phomopsis sp. BCC 9789.

Six new oblongolides, W1, W2, X, Y, and Z (1-3, 6, 7) and 2-deoxy-4alpha-hydroxyoblongolide X (4), and the known compounds oblongolide (8), oblongolides T, C, and Q (5, 9, 10), and (-)-5-methylmellein were isolated from the endophytic fungus Phomopsis sp. BCC 9789. Compound 7 showed anti-HSV-1 activity (IC50=14 microM) and cytotoxic activities against KB, BC, NCI-H187, and nonmalignant (Vero) cell lines with respective IC50 values of 37, 26, 32, and 60 microM. Cytotoxic activity against the BC cell line was also observed for compound 6, with an IC50 value of 48 microM.

Sesquiterpene lactone 12,8-eudesmanolides from the fungus Xylaria ianthinovelutina.

The investigation of Xylaria ianthinovelutina (Mont.) led to the isolation of four new 12,8-eudesmanolides (1-4). Their structures were determined by spectroscopy and the relative stereochemistry was assigned based on NOESY and CD spectral data. Compounds 1-4 exhibited biological activity against Plasmodium falciparum K-1 strain, NCI-H187, KB, MCF-7 with IC(50) values varying in the range 0.78-19.15 microg/mL.

Isariotins A-D, alkaloids from the insect pathogenic fungus Isaria tenuipes BCC 7831.

Isariotins A-D (1- 4), alkaloids possessing a unique bicyclo[3.3.1]nonane ring, were isolated from the insect pathogenic fungus Isaria tenuipes BCC 7831. The structures of these compounds were elucidated primarily by NMR and mass spectroscopic analyses.

Production of red pigments by the insect pathogenic fungus Cordyceps unilateralis BCC 1869.

Production of red pigments (naphthoquinones) by the insect pathogenic fungus Cordyceps unilateralis BCC 1869 was investigated in this study. Cultivation conditions, including temperature, intitial pH of medium, and aeration, were optimised to improve the yield of total naphthoquinones in shake-flask culture of C. unilateralis. The highest yield of total naphthoquinones (3 g L-1) was obtained from a 28-day culture grown in potato dextrose broth with an initial pH of 7.0, at 28 degrees C with shaking-induced aeration at 200 rpm. An extraction process for isolation of the targeted naphthoquinone, 3,5,8-trihydroxy-6-methoxy-2-(5-oxohexa-1,3-dienyl)-1,4-naphthoquinone (3,5,8-TMON), from a culture of C. unilateralis, was also developed. The yield of 3,5,8-TMON obtained was about 1.2 g L-1 or 40% of total naphthoquinones. The stability of 3,5,8-TMON was very high, even upon exposure to strong sunlight (70,000 lx), high temperature up to 200 degrees C, and acid and alkali solutions at concentrations of 0.1 M.

Ketene acetal and spiroacetal constituents of the marine fungus Aigialus parvus BCC 5311.

Aigialone (1) and aigialospirol (2), two structurally unique compounds, were isolated from the mangrove fungus Aigialus parvus BCC 5311. The structure of the new ketene acetal 1 was elucidated by spectral analysis, and its relative stereochemistry was determined by X-ray crystallography. The stereochemistry of aigialospirol (2), elucidated by NMR spectral analysis, suggested that this compound is possibly derived from hypothemycin (3), a metabolite previously isolated from this same fungus.