No abstract

Outer membrane alterations were characterized in spontaneous mutants of the Erwinia chrysanthemi 3937jRH, which were selected for resistance to bacteriophage +EC2. All but one of the mutants analyzed were affected in their lipopolysaccharide (LPS) structure, lacking the entire heterogeneous region of apparent high molecular weight present in the wild-type E. chrysanthemi LPS. At least two 3937jRH mutants, one selected as 4EC2 resistant (RH6065) and the other previously selected (D. Expert and A. Toussaint, J. Bacteriol. 163:221-227, 1985) as bacteriocin resistant (R1456), were cross-resistant to bacteriophage Mu and had rough LPSs with an altered core structure. Two 4EC2r mutants (RH6053 and RH6065) were most severely affected in their outer membrane integrity and also lost their virulence on saintpaulia plants, although they still possessed normal extracellular levels of pectinolytic and cellulolytic activities. The two Mur mutants RH6065 and R1456 were also able to induce systemic resistance in the challenged plant. All the other 4EC2r mutants retained the virulence of 3937jRH.

Using an RP4 plasmid which carries a mini‐Mu prophage which allows it to integrate spontaneously random pieces of its host chromosome, we cloned in vivo at least some of the pectate lyase and cellulase genes of the Erwinia chrysanthemi strain B374. The RP4‐prime plasmids were used to localize the cloned genes on the B374 chromosome by co‐transposition mapping and to subclone most of the genes in a classic high copy number plasmid vector.

No abstract

We report experimental evidence that pULB113, an RP4::mini-Mu plasmid, mediates chromosome transfer in a strain of Erwinia carotovora subsp. chrysanthemi which does not accept the F episome. This allowed us to construct a genetic map of that strain by measuring the frequencies of cotransfer of different markers (thy, leu, pro, [his, trp], thyA, rpsL, ile).