Transfer of Drug Resistance to Myxococcus from Bacteria Carrying Drug-resistance Factors

Abstract

SUMMARY: Resistance to chloramphenicol was successfully transferred from strains of Escherichia coli carrying R factors representative of compatibility groups F, W, S and N to strains of Myxococcus xanthus and M. fulvus. Resistance to kanamycin was transferred from an R factor in group S, and to neomycin from an R factor of group P. Myxobacterial strains differed in their capacity to take up the resistances and also in the stability of the resistance character. Strains of M. fulvus were obtained that acquired resistance to chloramphenicol without exposure to R- eubacterial strains. Cell-free preparations of all the chloramphenicol-resistant strains catalysed the acetylation of the drug. Chloramphenicol resistance was successfully transferred from the presumed R+ strains of Myxococcus and also from the spontaneously occurring chloramphenicol-resistant M. fulvus to other Myxococcus strains. Moreover, recombinants resistant to both rifampicin and 5-fluorouracil were obtained, though infrequently, mixing Myxococcus strains resistant to rifampicin and chloramphenicol with other myxococci resistant to 5-fluorouracil, both when the chloramphenicol resistance was derived from S-a (group W) and when it was the endogenous M. fulvus resistance. Thus it appears that S-a and a new chloramphenicol resistance factor from M. fulvus will mobilize a chromosomal genetic marker in Myxococcus.