Action of ABS on Microgranisms

Abstract

The antibacterial property of alkylbenzene sulfonates (ABS) was studied with E. coli, Staph. aureus and B. subtilis.The adsorption of ABS and cetyl trimethyl ammonium bromide (CTAB) on B. subtilis or E. coli at various pH levels was studied. It was found that ABS was easily adsorbed on those organisms in acidic side but CTAB was easily adsorbed on them in higher pH range.The differences in the growth inhibitory action of ABS and CTAB against Staph. aureus by the difference of pH range were investigated. It was found that the minimal growth inhibitory concentration was 2.5μg/ml below pH 5, 20μg/ml above pH 7 for ABS and 0.255μg/ml above pH 7, 0.51μg/ml at pH 6 for CTAB. From those results, the electrostatic adsorption of the surfactant on bacteria is one of the important factors concerning its antibacterial action.The bactericidal action of ABS and alkyl dimethylbenzyl ammonium chloride (ADBAC) against E. coli and Staph. aureus in nonvegetative stage of growth was studied. It was found that the exponent, n, of dilution coefficient of ABS was 0.20.6 for test organisms, therefore, discussion of bactericidal activity of ABS in comparison with well known phenol coefficient is meaningless. The adsorption of ABS on the organisms, decrease in the number of living organisms, turbidity change of bacterial suspension and permeation of cellular contents, such as proteins and nucleic acid were observed.The turbidity change of liquid medium was observed by addition of ABS in the logarithmic growth phase of Staph. aureus.From these experiments, it is suggested that the permeability change of cell membrane and bacteriolysis resulting from denaturation of cellular proteins due to the adsorption of ABS is included in the mechanisms of the antibacterial action of ABS.