ISSN: 0973-7510

E-ISSN: 2581-690X

Research Article | Open Access

Jirayu Buatong1, Vatcharin Rukachaisirikul2, Suthinee Sangkanu1, Frank Surup3 and Souwalak Phongpaichit1

1Department of Microbiology and Natural Product Research Center of Excellence, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla, Thailand.
2Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla, Thailand.
3Department of Microbial Drugs, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany.
J Pure Appl Microbiol, 2019, 13 (2): | Article Number: 5592

© The Author(s). 2019 

Received: 11/04/2019| Accepted: 09/05/2019 | Published: 14/06/2019
Abstract

Marine-derived actinobacteria are considered as potential sources of bioactive metabolites including antifungal substances. Fifteen out of 155 marine-derived actinobacteria exhibited strong antifungal activity against the rice blast fungus Pyricularia oryzae. Their extracts were further determined for minimum inhibitory concentrations (MIC) and minimum fungicidal concentrations (MFC). Ethyl acetate extract from the strain AMA49 and its subfraction AMA49F1 strongly inhibited hyphal growth of various P. oryzae strains with MICs (8 to 16µg/ml) and MFCs (16 to 128µg/ml) comparable to propiconazole. Both extracts destroyed fungal membrane and organelles, completely inhibited conidial germination, appressorium formation, and were non-toxic to Galleria mellonella. High performance liquid chromatography/mass spectrometry identified oligomycin A and its derivatives as the active components of AMA49F1 besides several diketopiperazines. AMA49 was identified as a Streptomyces sp. based on morphological characteristics and 16S rDNA sequence analysis. The results suggest that the Streptomyces sp. strain AMA49 is a potential biocontrol agent against rice blast pathogen P. oryzae. This is the first report on the inhibitory effect of the marine-derived Streptomyces extract containing oligomycin A and its derivatives on mycelial growth, conidial germination and appressorium formation of P. oryzae.

Keywords

Marine-derived Streptomyces sp., Pyricularia oryzae, rice blast disease, diketopiperazines, oligomycin A.

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© The Author(s) 2019. Open Access. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License which permits unrestricted use, sharing, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.