Figure 1: Molecular visualization of capsule deletion of the serotype 7F meningitis isolate. A) Both wild type (wt, filled line with squares) and capsule deficient mutant (Δcps,filled line with triangels) showed similar growth behavior in complete medium. In contrast to the wild type strain (wt+AB, dotted line with circles) growth behavior of 7F-isolate1Δcps (Δcps+AB, dotted line with squares) was not impaired in medium supplemented with kanamycin. Standard deviation was calculated from triplicates, the growth curves were repeated twice. B) Southern blot hybridization was performed after separation of HindIII-digested genomic DNA from the 7F-isolate1 (7F wt, lane 2), the capsule mutant (7F Δcps, lane 3). The pcr product of the mutagenesis fragment was used as control probe for hybridization in lane 1 (ctrl). HindIII-digested genomic DNA of D39 (D39 wt) and corresponding capsule negative mutant (D39 Δcps) representing well described comparative controls were probed in lane 5, 6. Southern blot analyses confirmed insertion of the kanamycin resistance cassette and loss of capsule gene locus resulting in reduced fragment size (arrow). C) Transmission electron microscopic visualization of capsule expression after labeling with cationic nanogold-particles. Capsule surrounded the 7F wild type bacteria (7Fwt, black arrows). Deletion of capsular polysaccharides resulted in loss of carbohydrate structures covering the cell wall (7FΔcps, arrow heads). Size scale represents 500 nm (left panel) and 200 nm (middle and right panel).