Bactericidal activity of peracetic acid to selected fish pathogens in recirculation aquaculture system water

Authors: GOOD, CHRISTOPHER - Freshwater Institute; REDMAN, NATALIE - Freshwater Institute; MURRAY, MEGAN - Freshwater Institute; Straus, David - Dave; Welch, Timothy - Tim

Submitted to: Aquaculture Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/25/2022
Publication Date: 8/2/2022
Citation: Good, C., Redman, N., Murray, M., Straus, D.L., Welch, T.J. 2022. Bactericidal activity of peracetic acid to selected fish pathogens in recirculation aquaculture system water. Aquaculture Research. (53)16:5731-5736. https://doi.org/10.1111/are.16031.
DOI: https://doi.org/10.1111/are.16031

Interpretive Summary: Peracetic acid (PAA) has significant potential as a disinfectant in fish farming, although it is currently not approved in the United States for treating aquaculture systems when food fish are present. Baseline research is currently required, including determining PAA's efficacy as a disinfectant against important fish pathogens. It is known that PAA's efficacy is affected by water quality, and therefore research on its application in recirculation aquaculture systems (RAS) needs to be carried out in water representative of RAS culture. We therefore investigated PAA's efficacy against three important bacterial fish pathogens in RAS water: i) Yersinia ruckeri, ii) Weissella ceti, and iii) Flavobacterium columnare. For Y. ruckeri and F. columnare, 6-log disinfection was achieved after 5 min exposure to 5 mg/L and 3 mg/L PAA, respectively. Comparable disinfection was achieved for W. ceti at 10 mg/L following 10 min exposure. These data demonstrate that PAA is an efficacious disinfectant against the aforementioned pathogens at the tested concentrations and exposure times in the RAS water utilized.

Technical Abstract: Peracetic acid (PAA) has shown promise in the European Union as an efficacious, environmentally-friendly therapeutant for use in aquaculture. PAA is not currently approved in the United States for treating aquaculture systems when food fish are present, however, and baseline research is required focusing on numerous characteristics of PAA, including its efficacy as a disinfectant against important fish pathogens. The efficacy of PAA is known to be influenced by differences in the quality of water to which it is applied. Because recirculation aquaculture systems (RAS) are becoming more commonplace in the United States and elsewhere, and because RAS water often differs significantly in various characteristics compared to water in traditional flow-through systems, we sought to investigate the efficacy of PAA for disinfecting selected important bacterial fish pathogens in RAS water. We carried out disinfection experiments focusing on three pathogens: i) Yersinia ruckeri, ii) Weissella ceti, and iii) Flavobacterium columnare. For each pathogen, water was collected from on-site, fully operating RAS, and dosed with approximately 1.0 x 106 cells per 100 µL. PAA was then applied in triplicate at a range of concentrations to the pathogen-RAS water solutions, with exposure times of 0-, 2-, 5-, and 10-minutes prior to PAA neutralization. Colony forming units (CFU) were enumerated after plating neutralized solutions on nutrient agar and incubating at 30 oC for 24 h. For Y. ruckeri and F. columnare, 6-log reduction to 0 CFU / 20 µL was achieved after 5 min exposure to 5 mg/L and 3 mg/L PAA, respectively. Comparable disinfection was achieved for W. ceti at 10 mg/L following 10 min exposure. These data demonstrate that PAA is an efficacious disinfectant against the aforementioned pathogens at specific concentrations and exposure times in RAS water. Specific characteristics of the RAS water utilized, however, need to be taken into consideration when interpreting these results.