Antifungal activity and molecular identification of endophytic fungi from the angiosperm Rhodomyrtus tomentosa

Problems associated with fungal resistance to antifungal agents are increasing worldwide. There is need to find sources of novel antifungal drugs and endophytic fungi could be another interesting source. In this study, 213 culturable endophytic fungi isolated from leaves and branches of Rhodomyrtus tomentosa from Thailand were screened for their ability to produce antifungal agents. Crude extracts from 177 out of 213 fungal isolates exhibited inhibitory activity against human pathogenic fungi, evaluated by a microbroth dilution method. Of the 349 active extracts out of 617 extracts tested, 43.5% inhibited Penicillium marneffei; 16.5 to 20.8% inhibited two strains of Cryptococcus neoformans; 6.0% Microsporum gypseum; 5.0% Candida albicans, with minimal inhibitory concentrations (MIC) of 1 to 200 μg/ml. 22 endophytic fungi showing strong antifungal activity (MICs of 1 to 8 μg/ml) were identified by morphological and molecular methods. They mainly belonged to the genera Colletotrichum, Diaporthe, Guignardia and Phomopsis. The results of this work indicate that endophytic fungi from R. tomentosa can be a good source of potential antifungal natural products.Keywords: Rhodomyrtus tomentosa, antifungal activity, endophytic fungi, molecular identificatio

ความสัมพันธุ์ทางสายพันธ์ของราทะเลแอสโคไมโคตา

Doctor of Philosophy (Microbiology

การสำรวจและศึกษาเชื้อราในแหล่งน้ำบริเวณเขตรักษาพันธุ์สัตว์ป่าโตนงาช้าง จังหวัดสงขลา

Thesis (M.Sc., Microbiology)--Prince of Songkla University, 200

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 Cymodoceaserrulata (Family Cymodoceaceae), Halophilaovalis and Thalassiahemprichii (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 Microsporumgypseum and Penicilliummarneffei. 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

Diversity of higher marine fungi at Hat Khanom-Mu Ko Thale Tai National Park, Southern Thailand

Species occurrence and distribution of higher marine fungi at Hat Khanom-Mu Ko Thale Tai National Park, Nakhon SiThammarat Province, Southern Thailand was investigated. Four collections from four sites yielded 112 higher marine fungirepresenting 79 ascomycetes, 3 basidiomycetes, 30 anamorphic fungi, while others await further identification. Average percentageoccurrence of fungi recorded ranged from 0.05-11.3%. Species diversity, richness, and evenness were greatest atSite IV, Ao Tok, Koh Taen. The most frequently encountered taxa for all sites (>10%) were Corollospora maritima andLindra thallasiae. Lindra thallasiae and Swampomyces aegyptiacus were recorded for the first time in Thailand

Thai marine fungal diversity

The marine fungal diversity of Thailand was investigated and 116 Ascomycota, 3 Basidiomycota, 28 anamorphic fungi, 7 Stramenopiles recorded, with 30 tentatively identified. These species have primarily been collected from driftwood and attached decayed wood of mangrove trees. The holotype number of 15 taxa is from Thailand and 33 are new records from the country

Antimicrobial activities of fungi derived from the gorgonian sea fan <i>Annella</i> sp. & their metabolites

1491-1498One hundred and sixty-three fungi isolated from gorgonian sea fan Annella sp. were screened for antimicrobial activity against human pathogens. Forty-seven percents of the isolates produced antimicrobial metabolites against at least one pathogen with minimum inhibitory concentrations (MIC) ranged from 1 to 1,280 µg mL-1. Crude extracts from 16%, 21%, 18% and 23% of the isolates inhibited standard strain of Staphylococcus aureus, methicillin-resistant S. aureus, Escherichia coli and Pseudomonas aeruginosa, respectively. Eighteen percents of the isolates displayed antifungal activity against Microsporum gypseum while only 3% inhibited Cryptoccocus neoformans and Candida albicans. Potential isolates were identified by morphological and molecular characteristics. Twenty-nine pure compounds isolated from ten isolates were evaluated for antimicrobial activity. Griseofulvin from Nigrospora sp. PSU-F13 exhibited the best activity against M. gypseum (MIC 2 µg mL-1). The result indicates that sea fan-derived fungi are a potential source of antimicrobial agents

Scanning electron micrographs of test microorganisms with strongly active crude extracts.

<p><i>Cryptococcus neoformans</i> ATCC 90112 (A–E), <i>Cryptococcus neoformans</i> ATCC 90113 (F), <i>Candida albicans</i> NCPF 3153 (G–I) and a clinical isolate of <i>Microsporum</i><i>gypseum</i> (K–L) after incubation with 10% DMSO (A, G and J), amphotericin B (B and H), miconazole (K), hexane extract from the mycelia of <i>Penicillium</i> sp. PSU-ES43 (C), hexane extract from the mycelia of PSU-ES190 (D), ethyl acetate extract from the mycelia of <i>Fusarium</i> sp. PSU-ES73 (E and F), ethyl acetate extract from the mycelia of <i>Trichoderma</i> sp. PSU-ES38 (I), and hexane extract from the mycelia of Hypocreales sp. PSU-ES26 (L) for 16 h at 4 times their MIC values.</p

Phylogenetic tree based on ITS1-5.8S-ITS2 sequences of strongly active endophytic fungi.

<p>The number of each branch point represents percentage bootstrap support from Maximum Parsimony (MP BS) and Neighbour Joining (NJ BS) with 100 replications shown on the branch. MP BS values ≥50% are shown before the slash; NJ BS values ≥50% are shown after the slash. Length; 37 steps; consistency index (CI); 0.8108; retention index (RI); 0.9391; homoplasy index (HI); 0.1892; rescaled consistency index (RC); 0.7615.</p