Hp. Cheng et Tg. Lessie, MULTIPLE REPLICONS CONSTITUTING THE GENOME OF PSEUDOMONAS-CEPACIA-17616, Journal of bacteriology, 176(13), 1994, pp. 4034-4042
Macrorestriction fragment analysis of DNA from Pseudomonas cepacia 176
16, in conjunction with Southern hybridization experiments using junct
ion fragments containing rare restriction enzyme sites as probes, indi
cated that this bacterium contains three large circular replicons of 3
.4, 2.5, and 0.9 megabases (Mb). Inclusion of the 170-kb cryptic plasm
id present in this strain gave an overall estimate of genome size of 7
Mb. Other Southern hybridization experiments indicated that the three
large replicons contained rRNA genes as well as insertion sequence el
ements identified previously in this strain. The distribution of SwaI,
PacI, and PmeI sites on the three replicons was determined. A derivat
ive of Tn5-751 carrying a S,waI site was used to inactivate and map ge
nes on the 2.5- and 3.4-Mb replicons. Mutants were isolated in which t
he 2.5- and 0.9-Mb replicons had been reduced in size to 1.8 and 0.65
Mb, respectively. The loss of DNA from the 2.5-Mb replicon was associa
ted with lysine auxotrophy, beta-lactamase deficiency, and failure to
utilize ribitol and trehalose as carbon and energy sources. DNA fragme
nts corresponding in size to randomly linearized forms of the differen
t replicons were detected in unrestricted DNA by pulsed-field gel elec
trophoresis. The results provide a framework for further genetic analy
sis of strain 17616 and for evaluation of the genomic complexities of
other P. cepacia isolates.