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Abstract
Aquaponics is a sustainable agricultural method that is increasing in commercialization, although few studies have investigated the potential food safety hazards within commercial systems. From October 2020-September 2022, a longitudinal study assessed the potential microbial hazards found within an aquaponic farm and on the edible portion of the produce. Aeromonas hydrophila, an emerging foodborne pathogen, was identified as a resident microorganism in the aquaponic system and on produce grown in the system. A. hydrophila was isolated from 59.50% of collected samples (623/1,047), while Listeria monocytogenes, Shiga toxin-producing Escherichia coli, and Salmonella enterica were not identified in the system. An evaluation was performed on the biofilm formation of A. hydrophila in water collected throughout the aquaponic system and on aquaponic substrata. A. hydrophila was able to form biofilm in all aquaponic water and on common aquaponic material. Water from the beginning of the deep-water culture (DCW) supported the greatest A. hydrophila biofilm biomass, while water from the end of the DWC supported the least biofilm biomass (p < 0.05). Water from the fish tank supported the greatest cell density within the biofilm, while water from the end of DWC supported the lowest cell density (p < 0.05). Food and Drug Administration (FDA)- approved aquaculture drugs and Environmental Protection Agency sanitizers were evaluated for their minimum bactericidal activity and their efficacy on A. hydrophila planktonic and biofilm cells. All antimicrobials were able to completely kill A. hydrophila planktonic cells. Chloramine-T, potassium peroxymonosulfate, iodine, peracetic acid, and sodium hypochlorite had an MBC below the recommended concentration in aquaponic water (p < 0.05). Overall, sanitizer efficacy was reduced in aquaponic water compared to sterile deionized water on both planktonic and some sanitizer on biofilm cells. This research provides an understanding of potential pathogen found in the aquaponic system and mitigation methods that farms could use to reduce pathogen transmission while not inhibiting the beneficial bacteria.