Generation and characterization of a long-lasting reactive bromine antimicrobial system by ozonation of bittern

Ozonated water is a promising disinfectant for poultry processing, but its practical use is constrained by limited persistence and ozone off-gassing. This study characterized the persistent antimicrobial activity generated by ozonation of bittern, identified its precursor, and evaluated the resulting solution against diverse microorganisms. Bittern diluted with water (1:2, v/v) was subjected to microbubble ozonation for 30 min. The standardized ozonated bittern solution showed a total oxidizing capacity of 140–160 mg O₃ equivalents/L and a bactericidal dilution titer of ≥2,000-fold against Escherichia coli , while dissolved ozone remained below the detection limit. Major chloride constituents of bittern did not reproduce this activity, whereas ozonation of sodium bromide generated strong bactericidal activity, supporting bromide as an important precursor. During prolonged ozonation of sodium bromide, bactericidal activity plateaued while total oxidizing capacity continued to increase. Bromate was detected at 110.3 ± 16.0 mg/L. Ozonated bittern retained bactericidal activity for at least two months during storage, with greater preservation of activity at 4°C than at 25°C. Antimicrobial activity decreased with increasing fetal bovine serum concentrations. The ozonated bittern solution was active against Gram-negative and Gram-positive vegetative bacteria, bacterial endospores, fungi, SARS-CoV-2, and avian influenza virus H5N3; H5N3 infectivity was reduced by ≥7.0 log₁₀. These findings indicate that ozonation of bittern generates a persistent, broad-spectrum antimicrobial system associated with bromide-derived reactive species rather than residual dissolved ozone, although individual reactive bromine species were not directly quantified. Bromate formation represents an important safety consideration, and further chemical characterization and optimization are required before practical application in food-processing environments.