FREQUENCY AND DIVERSITY OF ANTIBIOTIC PRODUCTION BY PUTATIVE ERWINIA-HERBICOLA STRAINS

The frequency and diversity of antibiotic production by putative Erwin ia herbicola strains were investigated. Of 346 putative Erw. herbicola strains isolated from plants in various regions of France, 42% produc ed antibiotics on a glycerol-ammonium medium that were inhibitory to E rw. amylovora, the fire-blight pathogen. Of the 90 strains studied in detail that produced antibiotics, 84 produced types of antibiotics tha t were not toxic to Erw. amylovora (strain CFBP3051) in the presence o f different amino acids. On the basis of the amino acids that inhibite d the toxicity of the antibiotics to CFBP3051, the 90 strains could be divided into 13 different groups. It is suggested that the effectiven ess of an antibiotic in inhibiting Erw. amylovora in vivo may depend o n the free amino acid composition of the plant.