Effect of superoxide dismutase gene inactivation on virulence of Pseudomonas aeruginosa PAO1 toward the silkworm, Bombyx mori.
To investigate the role of superoxide dismutase (SOD) in virulence against the silkworm, Bombyx mori, mutants of Pseudomonas aeruginosa PAO1 lacking manganese-SOD (PAO1sodM), iron-SOD (PAO1sodB), or both (PAO1sodMB) were generated. The mutants were injected into the hemocoel of B. mori. The virulence decreased in the order PAO1=PAO1sodM>PAO1sodB>PAO1sodMB. In particular, PAO1sodMB was avirulent at a dose of 10(5) cells or less. The sod double mutant PAO1sodMB was then complemented with either pSodM or pSodB in trans. In both the complemented strains, the virulence was partially restored. Of the two plasmids, pSodB contributed more to the virulence of P. aeruginosa against B. mori. The results of growth in B. mori hemolymph broth and microscopic analysis suggested that a longer lag phase and superoxide sensitivity correlated with decreased virulence in sod mutants. In conclusion, the SODs are required for full virulence of P. aeruginosa against B. mori and Fe-SOD is more important than Mn-SOD in the infection process.
Iiyama
Kazuhiro
K
Laboratory of Insect Pathology and Microbial Control, Institute of Biological Control, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka 812-8581, Japan. iiyama@grt.kyushu-u.ac.jp
Chieda
Yuuka
Y
Lee
Jae Man
JM
Kusakabe
Takahiro
T
Yasunaga-Aoki
Chisa
C
Shimizu
Susumu
S
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D012831:Bombyx / Q000382:microbiology*; D020868:Gene Silencing; D009154:Mutation; D011550:Pseudomonas aeruginosa / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity*; D013482:Superoxide Dismutase / Q000235:genetics* / Q000378:metabolism; D014774:Virulence
D001426:Bacterial Proteins; D013482:Superoxide Dismutase