Elizabeth A. Latham

Yersinia ruckeri is an important fish pathogen causing enteric redmouth disease. Antibiotics have traditionally been used to control this pathogen, but concerns of antibiotic resistance have created a need for alternative interventions. Presently, chlorate and certain nitrocompounds were tested against Y. ruckeri as well as a related species within the genus, Y. aleksiciae, to assess the effects of these inhibitors. The results reveal that 9 mM chlorate had no inhibitory effect against Y. ruckeri, but inhibited growth rates and maximum optical densities of Y. aleksciciae by 20–25% from those of untreated controls (0.46 h⁻¹ and 0.29 maximum optical density, respectively). The results further reveal that 2-nitropropanol and 2-nitroethanol (9 mM) eliminated the growth of both Y. ruckeri and Y. aleksiciae during anaerobic or aerobic culture. Nitroethane, ethyl nitroacetate and ethyl-2-nitropropionate (9 mM) were less inhibitory when tested similarly. Results from a mixed culture of Y. ruckeri with fish tank microbes and of Y. aleksiciae with porcine fecal microbes reveal that the anti-Yersinia activity of the tested nitrocompounds was bactericidal, with 2-nitropropanol and 2-nitroethanol being more potent than the other tested nitrocompounds. The anti-Yersinia activity observed with these tested compounds warrants further study to elucidate the mechanisms of action and strategies for their practical application.