Abstract
Ten species of gram-negative bacilli (five strains each) were examined for the superoxide dismutase (SOD) and catalase activities with special reference to their virulence in mice by intraperitoneal challenge.
The SOD activities of P. aeruginosa strains (20 units or more/mg protein) were significantly higher than those of the other species tested. Of the tested strains, P. aeruginosa E7, E. coli No.94 and K. pneumoniae 3K25 had especially high SOD activities, i.e. 56.2-58.6units/mg protein and showed high virulence in mice. The results may indicate that the SOD activity is an important determinant for the virulence. On the other hand, the catalase activities of P. aeruginosa and P. stuartii were higher than that of any other species tested. Especially P. aeruginosa E7 and A14 had extremely high activities, i.e. 179 and 357units/mg protein, respectively. A close correlation between the bacterial virulence and the catalase activity was also found in all the strains of E. coli tested. However, in the mice challenged with E. coli, the catalase activity was considered to be more important than the SOD activity for the virulence.
