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

The influence of surface characteristics of the microorganisms acid the sub strate materials, such as electrokinetic potential and hydrophobicity, in t he adhesion process was investigated in a previous work [1]. As neither sur face charge nor hydrophobicity can fully explain the process of bacterial a dhesion, the effect of divalent cations was experimentally studied. Adhesio n 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, adhesio n was more favourable to the more negatively charged polymeric material. Th is points out a strong contribution of ion bridging in culture medium. In t he absence of divalent cations, a higher hydrophobicity of the support is r equired in the process of adhesion.