Figure 5
Characteristics of the NTUH-K9534 wild-type and its isogenic capsule deficient strains. (A) Differences in the hypermucoid phenotype are observed between the wild-type and its capsule deficient strains on the blood agar. (B) Under light microscopy, the wild-type strain K9534 produces an exopolysaccharide web attached to the capsule (original magnification, 1,000). The K9534 wza wzb-deletion mutant loses the capability of producing an exopolysaccharide capsule. (C) Serum sensitivity assays of resistance to killing by nonimmune healthy human serum of the K9534 wild-type and its wza wzb-deletion mutant strains. The data represent the means of three independent trials; the error bars represent the standard deviations. A mean survival ratio ≥1 corresponds to serum resistance. **P < 0.01 by Student’s t test (compared to the wild-type strain). (D) Spot tests of phages K5-2, K5-4 and the K5-4 ORF38 protein on the K9534 wild-type and its capsule deletion mutant strains. Phages (106 PFUs) or 1 μg K5 depolymerase were spotted on the plate, and a clear spot or a translucent spot, respectively, is observed.
