Generalized transduction of small Yersinia enterocolitica plasmids

Abstract

To study phage-mediated gene transfer in Yersinia, the ability of Yersinia phages to transduce naturally occurring plasmids was investigated. The transduction experiments were performed with a temperate phage isolated from a pathogenic Yersinia enterocolitica strain and phage mixtures isolated from sewage. Small plasmids (4.3 and 5.8 kb) were transduced at a frequency of 10(-5) to 10(-7)/PFU. However, we could not detect the transduction of any indigenous virulence plasmid (ca. 72 kb) in pathogenic Yersinia strains. Transductants obtained by infection with the temperate phage were lysogenic and harbored the phage genome in their chromosomes.

FIG. 1

Electron micrograph of temperate phage PY20 isolated from Y. enterocolitica. Bar, 100 nm.

FIG. 2

Restriction endonuclease cleavage maps of p29807neo and p49neo. nptII, neomycin resistance gene.

FIG. 3

Plasmid profiles of the Y. enterocolitica donor strains and recipient strain used for generalized transduction and of two transductants. Lanes: 1, marker DNA (phage lambda DNA digested with HindIII); 2, Y. enterocolitica 13169 (recipient); 3, Y. enterocolitica 13169(p49neo) (donor); 4, transductant containing p49neo; 5, Y. enterocolitica 13169 (p29807neo) (donor); 6, transductant containing p29807neo.

FIG. 4

Southern hybridization of phage PY20 DNA with total DNA from Yersinia strains. All DNAs were digested with HindIII and separated on an 0.8% agarose gel followed by Southern blotting. Lanes: 1, PY20; 2, empty; 3, Y. enterocolitica 29820 (original host strain of PY20); 4, Y. enterocolitica 13169 (recipient for the transduction experiments); 5 to 9, total DNA of five transductants.