[The effect of gene deletion in on capsule formation and bacteriophage sensitivity].

To investigate the effects of gene deletion in on capsule formation ability and bacteriophage sensitivity. The deletion mutant strain was constructed through a temperature-sensitive plasmid-mediated homologous recombination. The growth curves of W14 and Δ were detected by measuring the optical density OD. In order to analyze the effect of gene on bacterial capsule formation, wild-type strain W14 and Δ mutant strain were detected by transmission electron microscope, and their capsule contents were measured by quantifying the uronic acid contents. The plaque assay was used to detect bacterial sensitivity to bacteriophage in wild-type strain W14 and Δ mutant strain. The test was used to compare whether there were differences in the contents of uronic acid in the capsules of wild-type strain W14 and Δ mutant strain. The PCR results revealed that the Δ mutant strain was successfully constructed. Compared with wild-type strain W14, the growth curves of Δ on the solid plates demonstrated a slightly slower growth. However, no difference in growth was observed among wild-type strain W14 and Δ mutant strains in LB broth. The transmission electron microscope results showed that gene deletion resulted in the loss of capsule in bacteria. The uronic acid content assay suggested that the capsule content was significantly decreased in Δ mutant strain (45.963±2.795) μg/ml compared with wild-type strain W14 (138.800±5.201) μg/ml. There was a statistical difference between the two groups (=27.233, 0.001). The plaque assay indicated that bacteria lost its sensitivity to bacteriophage when gene was deleted. Deletion of the gene impairs bacterial capsule formation ability and can affect bacterial sensitivity to bacteriophage phiW14.