Inhibitory effect of select nitrocompounds and chlorate against Yersinia ruckeri and Yersinia aleksiciae in vitro

Authors: LATHAM, ELIZABETH - Texas A&M University; Anderson, Robin; WOTTLIN, LAUREN - Former ARS Employee; Poole, Toni; Crippen, Tawni - Tc; SCHLOSSER, WAYNE - Food Safety Inspection Service (FSIS); Harvey, Roger; Hume, Michael

Submitted to: Pathogens
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/16/2022
Publication Date: 11/19/2022
Citation: Latham, E.A., Anderson, R.C., Wottlin, L.R., Poole, T.L., Crippen, T.L., Schlosser, W.D., Harvey, R.B., Hume, M.E. 2022. Inhibitory effect of select nitrocompounds and chlorate against Yersinia ruckeri and Yersinia aleksiciae in vitro. Pathogens. 11. Article 1381. https://doi.org/10.3390/pathogens11111381.
DOI: https://doi.org/10.3390/pathogens11111381

Interpretive Summary: Yersinia ruckeri is a group of bacteria that cause an economically important disease in wild and farmed fish, called enteric redmouth disease. Antibiotics have traditionally been used to control these disease-causing bacteria. There are concerns that these bacteria as well as other bacteria in natural water environments may develop resistance to the antibiotics. This has created a need for new non-antibiotic strategies to control the disease. In this study, we tested the potential of a chemical called chlorate and certain chemicals referred to as nitrogen-containing compounds to help decrease Y. ruckeri as well as a related bacterium, Yersinia aleksiciae. Results revealed that the chemical chlorate had no inhibitory effect against Y. ruckeri but did decrease the rate of growth of Y. aleksciciae by 20-25% when compared to untreated controls. Results further revealed that 2 nitrogen-containing chemicals, nitropropanol and nitroethanol, each eliminated the growth of both Y. ruckeri and Y. aleksiciae when tested under laboratory conditions. Results from studies simulating real world conditions revealed that the chemicals nitropropanol and nitroethanol are each very potent against Y. ruckeri and Y. aleksiciae. The results of this work will ultimately lead to new antimicrobial treatments to control the bacterial cause of redmouth disease in fish and may ultimately yield antimicrobial treatments against bacteria within the group of Yersinia bacteria, including some that are foodborne pathogens. This research will help reduce costs of food production, thereby helping to produce safer food at less cost for the American consumer.

Technical Abstract: Yersinia ruckeri is an important fish pathogen causing a disease called enteric redmouth disease. Antibiotics have traditionally been used to control this pathogen, but concerns of antibiotic resistance incentivize a need for alternative interventions. Presently, chlorate and certain nitrocompounds were tested against Y. ruckeri as well as a more centrally-related species within the Genus, Y. aleksiciae, to assess the effects of these inhibitors. Results revealed 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 (0.29 ODmax and 0.46 h-1, respectively). Results further revealed that 2-nitropropanol and 2-nitroethanol (9 mM) each eliminated growth of both Y. ruckeri and Y. aleksiciae during anaerobic or aerobic culture. Nitroethane, ethyl nitroacetate, or ethyl-2-nitropropionate (9 mM) were less inhibitory when tested similarly. Results from mixed culture of Y. ruckeri with fish tank microbes and of Y. aleksiciae with porcine fecal microbes revealed 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 mechanisms of action and strategies for their practical application.