CHANGES OF SURFACE-CHARGE AND HYDROPHOBICITY OF THE OUTER BACTERIAL-MEMBRANE DEPENDING ON THE CULTIVATION MEDIUM

The changes of surface charge and hydrophobicity of the outer bacteria l membrane in relation to utilization of n-hexadecane were studied. Fo r this spectrophotometric study adsorption of methylene blue and trans port of gentiane violet were used. We have found out that the decrease of negative charge of investigated bacterial strains-Pseudomonas puti da CCM 3423, P. aeruginosa and P. fluorescens CCM 2115 depends on the type of growth media. The decrease of surface charge was in the order: meat extract peptone broth > mineral medium with glucose > mineral me dium with n-hexadecane. We have also determined the highest permeabili ty of bacterial membrane for gentian violet in the case of P. fluoresc ens grown in meat extract peptone broth. This effect can be explained by a greater hydrophobicity of bacterial surface of this strain. In th e case of other examinated strain lower permeability was observed. P. fluorescens showed also a better adherence to hexadecane.