Mechanism of the Initial Events in the Sorption of Marine Bacteria to Surfaces

Abstract

The sorption of two marine bacteria to surfaces involved an instantaneous reversible phase, and a time-dependent irreversible phase. Reversible sorption of the non-motile Achrornobacter strain R 8 decreased to zero as the electrolyte con- centration decreased, or as the thickness of the electrical double-layer increased. The electrolyte concentration at which all bacteria were repelled from the glass surface depended on the valency of the cation. The reversible phase is interpreted in terms of the balance between the electrical double-layer repulsion energies at different electrolyte concentrations and the van der Waals attractive energies. Even at the electrolyte concentration of seawater, the bacteria probably are held at a small distance from the glass surface by a repulsion barrier. Reversible sorption often led to rotational motion of the motile Pseudornonas sp. strain ~3 at a liquid-glass interface. Pseudomonas ~3 produced polymeric fibrils in artificial seawater; these may be concerned in the irreversible sorption of the bacteria to surfaces. Sorption and polymer production were stimulated by 7 mg./l. glucose but higher levels inhibited irreversible sorption. Omission of Ca2+ and Mg2+ from the artificial seawater prevented growth, polymer production, and sorption to surfaces by Pseudomonas R3- INTRODUCTION