Toxicity of dodecylpyridinium and cetylpyridinium clorides against phosphate-accumulating bacterium

The antibacterial effect of cationic surfactants against the pure culture of phosphate (P)-accumulating bacterium Acinetobacter junii was investigated. The estimated EC₅₀ values of the N-dodecylpyridinium chloride (DPC) for growth inhibition was 1.4±0.5 × 10⁻⁶ mol L⁻¹ and for the inhibition of the P-uptake rates 7.3±2.6 × 10⁻⁵ mol L⁻¹. The estimated EC₅₀ values of the N-cetylpyridinium chloride (CPC) for growth inhibition was 4.9±1.3 × 10⁻⁷ mol L⁻¹ and for the inhibition of the P-uptake rates 7.7±2.9 × 10⁻⁶ mol L⁻¹. This suggests the importance of controlling the amounts of cationic surfactants in influent of the wastewater treatment systems in order to avoid the possible failure of the biological P removal from wastewaters.