Jariya Sakayaroj

Phylogenetic diversity of endophyte assemblages associated with the tropical seagrass Enhalus acoroides in Thailand

Seagrasses are flowering plants inhabiting coastal and marine environments, with a worldwide distribution. They serve as feeding, breeding and nursery grounds for economically important marine organisms including endangered species. The tropical seagrass Enhalus acoroides was collected from Had Khanom-Mu Ko Thale Tai National Park, southern Thailand. The objectives of this study were to investigate for the presence of endophyte assemblages in E. acoroides, as well as to describe the diversity of endophytes based on LSU, ITS1, 2, 5.8S rDNA sequence analyses. Forty-two fungal assemblages were isolated and identified through molecular data. This resulted in a diversity of fungal groups of Ascomycota (98%) and Basidiomycota (2%). Three major Ascomycota classes including the Sordariomycetes (36%), Eurotiomycetes (33%) and Dothideomycetes (24%) were determined. The predominant ascomycete orders were the Hypocreales, followed by the Eurotiales and the Capnodiales, respectively. Additionally one taxon belonged to the Russulales, Basidiomycota and was possibly mycorrhiza. This study confirms that E. acoroides harbors a wide diversity of fungal endophytes, and provides a baseline for further studies on fungal-host plant interactions.

Anthraquinone, cyclopentanone, and naphthoquinone derivatives from the sea fan-derived fungi Fusarium spp. PSU-F14 and PSU-F135.

Five new metabolites, fusaranthraquinone (1), fusarnaphthoquinones A-C (2-4), and fusarone (5), were isolated from the sea fan-derived fungi Fusarium spp. PSU-F14 and PSU-F135 along with 18 known compounds. The structures were elucidated on the basis of spectroscopic evidence. Their antibacterial, antifungal, antimycobacterial, antimalarial, and cytotoxic activities were examined.

Phthalide and isocoumarin derivatives produced by an Acremonium sp. isolated from a mangrove Rhizophora apiculata.

Nine new fungal metabolites, one phthalide derivative, acremonide (1), and eight isocoumarin derivatives, acremonones A-H (2-9), were isolated from the mangrove-derived fungus Acremonium sp. PSU-MA70 together with 10 known compounds. Their structures were determined by NMR analysis. The known 8-deoxytrichothecin and trichodermol exhibited moderate antifungal activity against Candida albicans and Cryptococcus neoformanns, respectively.

Metabolites from the endophytic fungus Xylaria sp. PSU-D14

Glucoside derivatives, xylarosides A (1) and B (2), were isolated from the broth extract of the endophytic fungus Xylaria sp. PSU-D14 along with two known compounds, sordaricin (3) and 2,3-dihydro-5-hydroxy-2-methyl-4H-1-benzopyran-4-one (4). The structures were assigned by spectroscopic methods. Sordaricin (3), one of the known metabolites, exhibited moderate antifungal activity against Candida albicans ATCC90028 with a MIC value of 32 microg/ml.

Sesquiterpene and Xanthone Derivatives from the Sea Fan-Derived Fungus Aspergillus sydowii PSU-F154

Three new sesquiterpenes, named aspergillusenes A and B and (+)-(7S)-7-O-methylsydonic acid, and two new hydrogenated xanthone derivatives, named aspergillusones A and B, were isolated from the sea fan-derived fungus Aspergillus sydowii PSU-F154 together with 10 known compounds. Their structures were identified on the basis of spectroscopic data. The isolated compounds were evaluated for their antioxidant activity.

Epoxydons and a Pyrone from the Marine-Derived Fungus Nigrospora sp. PSU-F5

Nigrospoxydons A-C (1- 3) and nigrosporapyrone (4), four new metabolites, were isolated from the marine-derived fungus Nigrospora sp. PSU-F5 together with nine known compounds. Their structures were elucidated by spectroscopic methods, mainly 1D and 2D NMR spectroscopic techniques. The antibacterial activity against the standard Staphylococcus aureus ATCC 25923 and methicillin-resistant S. aureus was evaluated.

Pyrone derivatives from the marine-derived fungus Nigrospora sp. PSU-F18.

Pyrones, named nigrosporapyrones A-D (1-4), and five known compounds were isolated from the marine-derived fungus Nigrospora PSU-F18. Their structures were elucidated on the basis of spectroscopic evidence. The antibacterial activity against the standard Staphylococcus aureus ATCC 25923 and methicillin-resistant S. aureus was evaluated.

Cyclohexene, diketopiperazine, lactone and phenol derivatives from the sea fan-derived fungi Nigrospora sp. PSU-F11 and PSU-F12

Nigrosporanenes A (1) and B (2), two new cylohexene derivatives, and tyrosol (3) were isolated from the sea fan-derived fungus Nigrospora sp. PSU-F11, whereas five known compounds: 4-hydroxybenzoic acid (4), aplysiopsene D (5), 3-isochromanone (6), (−)-drimenin (7) and diketopiperazine derivative (8), were obtained from the fungus Nigrospora sp. PSU-F12. Their structures were established by spectroscopic evidence. We also tested their cytotoxic (on African green monkey kidney fibroblast and breast cancer cells), antioxidant (in the DPPH assay), and antibacterial (against the standard Staphylococcus aureus ATCC 25923 and methicillinresistant S. aureus) activities.

Antimicrobial potential of endophytic fungi derived from three seagrass species: Cymodocea serrulata, Halophila ovalis and Thalassia hemprichii.

Endophytic fungi from three commonly found seagrasses in southern Thailand were explored for their ability to produce antimicrobial metabolites. One hundred and sixty endophytic fungi derived from Cymodocea serrulata (Family Cymodoceaceae), Halophila ovalis and Thalassia hemprichii (Family Hydrocharitaceae) were screened for production of antimicrobial compounds by a colorimetric broth microdilution test against ten human pathogenic microorganisms including Staphylococcus aureus ATCC 25923, a clinical isolate of methicillin-resistant S. aureus, Escherichia coli ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Candida albicans ATCC 90028 and NCPF 3153, Cryptococcus neoformans ATCC 90112 and ATCC 90113 and clinical isolates of Microsporum gypseum and Penicillium marneffei . Sixty-nine percent of the isolates exhibited antimicrobial activity against at least one test strain. Antifungal activity was more pronounced than antibacterial activity. Among the active fungi, seven isolates including Hypocreales sp. PSU-ES26 from C . serrulata , Trichoderma spp. PSU-ES8 and PSU-ES38 from H . ovalis , and Penicillium sp. PSU-ES43, Fusarium sp. PSU-ES73, Stephanonectria sp. PSU-ES172 and an unidentified endophyte PSU-ES190 from T . hemprichii exhibited strong antimicrobial activity against human pathogens with minimum inhibitory concentrations (MIC) of less than 10 µg/ml. The inhibitory extracts at concentrations of 4 times their MIC destroyed the targeted cells as observed by scanning electron microscopy. These results showed the antimicrobial potential of extracts from endophytic fungi from seagrasses.

Multi-gene phylogeny of the Halosphaeriaceae: its ordinal status, relationships between genera and morphological character evolution

The halosphaeriaceous fungi constitute the largest group of marine Ascomycota found predominantly in marine environments, with few transitional species found in freshwater and brackish water habitats. It has been one of the most intensively studied groups of marine fungi, with 126 species in 53 genera. The classification of the halosphaeriaceous fungi is contentious with one school maintaining that they should be regarded as a family in the Microascales, while others continue to retain the order Halosphaeriales. To refine the phylogenetic inter-relationships among the halosphaeriaceous fungi, 36 taxa were sequenced and analysed based on three loci [nuclear small and large subunit (SSU, LSU), the second largest RNA polymerase II subunit (RPB2)]. The halosphaeriaceous fungi constitute a monophyletic group and share a common ancestor with the Microascaceae however, they share few morphological characters. In the Halosphaeriaceae the centrum tissue comprises catenophyses; asci are clavate to fusiform; ascospores are hyaline, unicellular to many septate, usually with appendages, and most are saprobic in aquatic habitats. Whereas, the peridium of the Microascaceae is carbonaceous, frequently bearing hyphal appendages or setae; asci are globose or ovoid; ascospores are reniform, often bear ornamenting ridges or wings. Genera in the Microascaceae are mainly saprobic from soil to rotting vegetation and occasionally found as pathogens, and primarily terrestrial. Based on morphological data the halosphaeriaceous taxa might be considered as a group warranting ordinal status (Halosphaeriales) and this issue is discussed in this study. Sequence data also show clearly that the genera Remispora and Ceriosporopsis are polyphyletic and we propose the erection of three new genera to accommodate C. tubulifera (Toriella), R. crispa (Kochiella) and R. galerita (Tubakiella). Bovicornua intricata is referred to the genus Ceriosporopsis. The molecular data indicate that different phylogenies based on DNA sequences support a hypothesis that ascospore appendage developments e.g. unfurling bipolar appendages, have evolved and been lost several times.