HIGH-FREQUENCY DNA REARRANGEMENTS IN THE CHROMOSOMES OF CLINICALLY ISOLATED MYCOPLASMA-FERMENTANS

Mycoplasma fermentans is currently being examined as an agent potentia lly associated with human disease. Several strains of M. fermentans we re isolated from patients with respiratory tract disease and AIDS. Two of these clinical strains, M64 and SK6, were triple-filter-cloned and designated as the parental clones in this study. Genomic DNA of rando mly picked subclones in four and five subsequent generations passed fr om the parental M64 and SK6 clones were analyzed by using a radiolabel ed M. fermentans-specific insertion sequence (IS)-like element as the probe. The hybridization patterns of DNA restriction fragments reveale d high frequencies of chromosomal changes accompanied with excision or new insertion of the IS-like element in M. fermentans chromosome. The findings indicate M. fermentans has an effective mechanism(s) to prod uce a rapid gene rearrangement that may be mediated by one or more cop ies of the IS-like element.