Adhesion of Alcaligenes denitrificans to polymeric materials : the effect of divalent cations

Abstract

The influence of surface characteristics of the microorganisms and the substrate materials, such as electrokinetic potencial and hydrophobicity, in the adhesion process was investigated in a previous work [1]. As neither surface charge nor hydrophobicity can fully explain the process of bacterial adhesion, the effect of divalent cations was experimentally studied. Adhesion assays were performed in sodium phosphate buffer saline (PBS) medium and in a medium with the same ionic strength containing Ca2+, Mg2+ and Fe2+. In the presence of divalent cations, contrary to what happened in PBS, adhesion was more favourable to the more negatively charge polymeric material. This points out a strong contribution of ion bridging in culture medium. In the absence of divalent cations, a higher hydrophobicity of the support is required in the process of adhesion.