PRODUCTION OF 2,4-DIACETYLPHLOROGLUCINOL BY THE BIOCONTROL AGENT PSEUDOMONAS-FLUORESCENS PF-5

2,4-Diacetylphloroglucinol was detected in and isolated from culture e xtracts of the biological control bacterium Pseudomonas fluorescens Pf -5. Its structure was identified using a combination of chromatographi c techniques and NMR spectroscopic methods. Carbon source influenced 2 ,4-diacetylphloroglucinol production by Pf-5 in culture media. 2,4-Dia cetylphloroglucinol inhibited growth of the plant pathogenic fungi Pyt hium ultimum and Rhizoctonia solani, and the plant pathogenic bacteriu m Erwinia carotovara subsp. atroceptica, which cause diseases that are suppressed by strain Pf-5. The results of this study provide further evidence for the prevalence of 2,4-diacetylphloroglucinol production a mong strains of Pseudomonas fluorescens that suppress plant diseases.