INHIBITION OF SEPTORIA-TRITICI AND OTHER PHYTOPATHOGENIC FUNGI AND BACTERIA BY PSEUDOMONAS-FLUORESCENS AND ITS ANTIBIOTICS

Pseudomonas fluorescens strain PFM2, antagonistic to Septoria tritici, also inhibited growth of several other phytopathogenic bacteria and fungi in vitro. Three inhibitory compounds were extracted from liquid glycerol-peptone-phosphate medium in which strain PFM2 was grown for 4 weeks. The compound recovered in greatest quantity (70 mg/1) was identified as 2,4-diacetylpbloroglucinol. The other two antibiotics, which were produced in small amounts (<5 mg/1), were not identified. A similar pattern of inhibition against the different bacteria and fungi was exhibited by both 2,4-diacetylphloroglucinol and strain PFM2 when grown in a medium of the same composition as that in which the antibiotic was produced.