Genetic methods for the study of antibiotic resistance plasmids

Measuring Plasmid Conjugation Using Antibiotic Selection

Plasmid conjugation is intimately linked to the transmission of antibiotic resistances, and many naturally occurring plasmids carry antibiotic resistance genes. Here we describe classical methods based on the transmission of antibiotic resistance determinants routinely used to quantify plasmid conjugation under laboratory conditions. Methods described here are suitable for most plasmid incompatibility groups from Proteobacteria and can be readily adapted to other bacterial species.

Screening for plasmids in the genus Clostridium

A plasmid screening was performed on 150 strains out of 75 clostridial species using a modification of the alkaline-lysis procedure. In 26 strains representing 21 species one or more plasmid bands were detected ranging in size from 3 to more than 100 kilobase pairs. Clostridium aceticum proved to contain a single small plasmid (pCA1) of 5.4 kbp as revealed by restriction analysis and electron microscopy. A physical map of pCA1 has been constructed. Spontaneous mutants of C. aceticum defective in autotrophic growth have been isolated. No direct correlation between plasmid content and autotrophy could be found.