omp33 replacement. (a) Schematic representation of the linear DNA constructed for the omp33 gene replacement, which was completely deleted. The oligonucleotides used (small arrows) are listed in Table 2. (b) Screening of omp33 A. baumannii mutants generated by gene replacement. The numbers at the top are bacterial colony numbers. WT, Wild-type control with 2115 bp. Colonies 5 and 7 (lanes 5* and 7*) with 2214 bp (2115 bp - 834 bp [from omp33 deletion] + 933 bp [from kanamycin insertion]) were sequenced to confirm gene replacement. Lambda DNA-Hin d III and ϕX174 DNA-Hae III Mix (Finnzymes) was used as a size marker (M). The lengths of PCR products and of some molecular size marker fragments are also indicated.