Fig 1.
Colony morphology of PcyII-10 and phage-resistant variants.
Colonies formed by PcyII-10 and eleven variants plated at P3 on LB agar were photographed after 24 h at 37°C. The arrows point to lysis zones caused by phages. Variant V03 produces small colonies with irregular shapes. Variants V06, V07, V14 and V16 produce a reddish-brown pigment, the pyomelanin. Variants V17 and V19 were mucoid.
Fig 2.
Evaluation of Ab09 persistence in PcyII-10-V03.
(A) Colonies obtained after plating the P3 stock on a LB agar plate. (B) Fifty-two colonies recovered from the P3 stock were simultaneously plated using a sterilized pipette tip on LB agar (left) and on PcyII-10 embedded in soft agar overlay (right). The clear zone around the bacterial colony in the right panel is due to phage lysis of the indicator bacteria.
Fig 3.
Observation of pseudolysogens by electron microscopy.
Transmission electron micrograph of bacterial section from (A) The parental strain PcyII-10, (B) Variant PcyII-10-V07 and (C) Variant PcyII-10-V10. The arrow in (B) and (C) points to tightly packed material that might correspond to ribonucleoprotein particles. The scale bar corresponds to 200nm.
Fig 4.
Distribution of sequencing reads on the PcyII-10 genome forthree Ab09-resistant variants.
Mapping of sequencing reads to the genome of PcyII-10 revealed the existence of deleted zones. In variant PcyII-10-V02 no reads mapped to the Δ02 region, whereas in PcyII-10-V03 and PcyII-10-V15 the Δ03 and Δ15 regions were undeleted in an estimated 50% and 40% of cells respectively.
Table 1.
Characteristics of the mutations in the eleven phage resistant PcyII-10 variants.
Fig 5.
Analysis of ten deletions by PCR amplification and agarose gel electrophoresis.
For each deletion, two DNA samples were analysed, PcyII-10 and the corresponding variant. MW is for Molecular Weight marker, a 100bp fragment ruler from 100bp to 1000bp.
Table 2.
Susceptibility of the PcyII-10 variants and subvariants to phages.
Fig 6.
Comparison of Wzy and ORF1587 topologies using Protter.
Fig 7.
Plaque morphology of the large-plaque mutant of Ab09 produced by variant PcyII-10-V03.
Plaques produced by the wild type Ab09 phage have irregular fuzzy shapes and are surrounded by a halo whereas the Ab09-V03LP mutant forms large plaques with sharp edges and no halo.