Four strains, two from each of the plant pathogenic bacteria Pseudomonas and Erwinia, all producing bacteriocins, were submitted to different treatments in order to evaluate the persistance of bacteriocin production. After ethidium bromide treatment elimination of the bacteriocin production was achieved and the percentage of loss varied with the host strain and drug concentration. Elimination was not detected after treatment with high temperatures, above the normal ones. Also preservation of the strains for three years, in laboratory, did not cause elimination of the character. The curing of bacteriocin production after ethidium bromide treatment suggests that the involved genes are located in plasmids.
bacteriocine; Erwinia; Pseudomonas