Inhibition of <i>Septoria tritici</i> and other phytopathogenic fungi and bacteria by <i>Pseudomonas fluorescens</i> and its antibiotics

Abstract

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‐diacetylphloroglucinol. The other two antibiotics, which were produced in small amounts (&lt; 5 mg/l), 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.