Extrachromosomal DNA in chloramphenicol resistant myxococcus strains

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Extrachromosomal DNA, such as plasmids, plays a crucial role in bacterial adaptation and evolution.
• Understanding the genetic makeup of Myxococcus species is essential for their biotechnological applications.
• The presence and characteristics of extrachromosomal DNA in Myxococcus species have not been fully elucidated.

Purpose of the Study:

• To investigate the presence and nature of extrachromosomal DNA in Myxococcus xanthus and M. fulvus.
• To determine if chloramphenicol resistance in these species is associated with extrachromosomal DNA.
• To explore the transfer of antibiotic resistance via plasmids between Escherichia coli and Myxococcus species.

Main Methods:

• Rate-zonal centrifugation of radioactively-labeled DNA in cleared lysates.
• Induction of chloramphenicol resistance in M. xanthus.
• Conjugation experiments with R+ strains of Escherichia coli and Myxococcus species.
• Double-labeling techniques to compare DNA profiles.

Main Results:

• All examined Myxococcus strains, except M. xanthus FBt, contained extrachromosomal DNA.
• Induction of chloramphenicol resistance in M. xanthus FBt was linked to the production of a plasmid.
• Chloramphenicol resistance was successfully transferred to Myxococcus species from Escherichia coli R+ strains.
• Specific extrachromosomal DNA peaks were observed in chloramphenicol-resistant M. fulvus strains, particularly those derived from R factor S-a.

Conclusions:

• Extrachromosomal DNA is prevalent in Myxococcus xanthus and M. fulvus.
• Plasmids are likely involved in conferring chloramphenicol resistance in these bacteria.
• Horizontal gene transfer of antibiotic resistance is feasible between E. coli and Myxococcus species.