Susceptibility of strains of Aeromonas salmonicida to killing by cell-free generated superoxide anion

Abstract. Superoxide anion was generated in a cell-free system using photoreduced riboflavin and methionine. This allowed the susceptibility to killing by superoxide of 11 strains of Aeromonas salmonicida to be investigated. A good correlation was found between susceptibility and 'virulence factors' of the different strains. In the presence of an inhibitor of superoxide dismutase (sodium nitroprusside), the bactericidal effect of superoxide was increased, particularly in the more resistant strains, suggesting that these strains possess superoxide dismutase (SOD). The use of levels of detoxifying enzymes within bacteria such as SOD as an indicator of virulence is discussed.