Physiological changes induced by the quaternary ammonium compound benzyldimethyldodecylammonium chloride on Pseudomonas fluorescens

Results: The MIC was found to be 20 mg/L and the MBC was 10 mg/L. BDMDAC led to a significant change in cell surface hydrophobicity and induced propidium iodide uptake. Such results suggest cytoplasmic membrane damage, corroborated by the release of intracellular potassium. The results obtained from the zeta potential measurement demonstrate a 231.2 mV value for untreated cells and 221.0 mV for cells at the MIC. Scanning electron microscopy revealed that cells treated with 20 mg/L were less bulky, and their membrane seemed to be rougher, wrinkled and deformed when compared with untreated cells. The overall bactericidal events occurred without detectable changes in OMP expression. Conclusions: BDMDAC is an effective biocide against P. fluorescens. It binds by ionic and hydrophobic interactions to the cell membrane, causing changes in membrane properties and function, as manifested by phenomena such as cellular disruption and loss of membrane integrity with consequent leakage of essential intracellular constituents.