• Journal of Microbiology and Biotechnology
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• v.20 no.3
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• pp.494-500
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• 2010

Bacterial blight, an important and potentially destructive bacterial disease in rice, is caused by Xanthomonas oryzae. Recently, this organism has developed resistance to available antibiotics, prompting scientists to find a suitable alternative. This study focused on secondary metabolites of Phomopsis longicolla to target X. oryzae. Five bioactive compounds were isolated by activity-guided fractionation from ethyl acetate extracts of mycelia and were identified by LC/MS and NMR spectroscopy as dicerandrol A, dicerandrol B, dicerandrol C, deacetylphomoxanthone B, and fusaristatin A. This is the first time fusaristatin A has been isolated from Phomopsis sp. Deacetylphomoxanthone B showed a higher antibacterial effect against X. oryzae KACC 10331 than the positive control (2,4-diacetyphloroglucinol). Dicerandrol A also showed high antimicrobial activity against Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis) and yeast (Candida albicans). In addition, high production yields of these compounds were obtained at the stationary and death phases.

• Korean Journal Plant Pathology
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• v.14 no.5
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• pp.526-530
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• 1998

The effect of field sanitation using ecological characters of the pathogen was investigated for controlling Phomopsis seed decay in soybean. Field sanitation which was eliminated the inoculum by removing host debris, abscised petioles and cotyledones out of field, reduced remarkably infection percentage of pods and seeds by Phomopsis spp. as compared to the inoculated field. Neverthless, seed infection was 28.7% in the sanitized field. The fields sanitized by benlate application around the soybean plants also decreased seed infection with Phomopsis spp. Total seed infection including that with miscellaneous pathogens occurred as much as 75∼79% to the no application and their control values were 34∼42% over the routine application schedule. Even though it was not satisfactory, field sanitation seemed to be effective in controlling Phomopsis seed decay when infection pressure was low level. Diaporthe phseolorum va. sojae, D. phaseolorum var. caulivora and Phomopsis longicolla were mostly identified from soybean seeds and Colletotrichum truncatum, Cercospora kikuchiana were also isolated in sequence. Field sanitation did not significantly increase in soybean yield over the no application, while routine application schedule did in field.

• Journal of Microbiology and Biotechnology
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• v.23 no.2
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• pp.177-183
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• 2013

Bacterial blight, an important and potentially destructive bacterial disease in rice caused by Xanthomonas oryzae pv. oryzae (Xoo), has recently developed resistance to the available antibiotics. In this study, mass spectrometry (MS)-based metabolite profiling and multivariate analysis were employed to investigate the correlation between timedependent metabolite changes and antimicrobial activities against Xoo over the course of Phomopsis longicolla S1B4 fermentation. Metabolites were clearly differentiated based on fermentation time into phase 1 (days 4-8) and phase 2 (days 10-20) in the principal component analysis (PCA) plot. The multivariate statistical analysis showed that the metabolites contributing significantly for phases 1 and 2 were deacetylphomoxanthone B, monodeacetylphomoxanthone B, fusaristatin A, and dicerandrols A, B, and C as identified by liquid chromatography-mass spectrometry (LC-MS), and dimethylglycine, isobutyric acid, pyruvic acid, ribofuranose, galactofuranose, fructose, arabinose, hexitol, myristic acid, and propylstearic acid were identified by gas chromatography-mass spectrometry (GC-MS)-based metabolite profiling. The most significantly different secondary metabolites, especially deacetylphomoxanthone B, monodeacetylphomoxanthone B, and dicerandrol A, B and C, were positively correlated with antibacterial activity against Xoo during fermentation.