School of Engineering and Science - Jacobs University

Results
The signal for PCR fragment 1 is shifted as compared to Pss22d wt. This shift
is due to the insertion of the resistance cassette and the loss of a chromosomal
ApaLI site within the deleted sequence. Transformant no. 5 was designated
Pss22d∆Pvd and further analyzed for its siderophore phenotype. As expected,
Pss22d∆pvsA was no longer fluorescent when grown on King’s B medium
indicating the deficiency of the strain to produce pyoverdin (Fig.9A). But
surprisingly, it still produced a halo on CAS-agar almost as large as the wild
type strain (Fig.9B). This halo clearly indicated that mutant Pss22d∆pvsA
produces a functional siderophore although the pyoverdin biosynthesis of this
strain disrupted successfully.
5.1.2 Southern blot analysis of Psg1a and Pss22d for the presence of
yersiniabactin biosynthetic genes
At the time of construction of Pss22d∆Pvd, the first genome sequence of a
P. syringae was completed, namely the sequence of PsmDC3000. With the
finished annotation of the genome project, the presence of a yersiniabactin
biosynthesis cluster in PsmDC3000 was reported (Buell et al., 2003).
Pss22d∆Pvd
Pss22d
A
B
Fig. 9. Siderophore production of Pss22d and Pss22d∆Pvd.
A: Fluorescence of pyoverdin on Kings B medium; B: Siderophore production
on CAS agar. Bacterial suspension was applied to the respective medium and
incubated at 28°C for 48h.
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