Influence of surface properties on accumulation of conditioning films and marine bacteria on substrata exposed to oligotrophic waters

Abstract

The influence of interfacial wettabilities on initial conditioning and bacterial colonization of polished surfaces was examined in the oligotrophic, subtropical waters off O'ahu's south shore and in the laboratory. After exposures to seawater for 3 d, accumulations of attached bacteria on 11 types of substrata during two deployments varied as a second order function of substratum wettability. As observed in previous biomedical and mesotrophic field studies, surfaces with intermediate critical surface tensions (γcrit = 20–30 mN m‐1) and extremes in the polar and dispersive components of the composite surface free energy were least colonized by bacteria. Conditioning film thicknesses, varied by a factor of 100 among materials and also appeared to be a second order function of γcrit. Sorbed films produced interfaces with a range of wettabilities, dependent upon substratum and sorbate properties. Bacteria isolated from surfaces exhibited four basic partitioning patterns into non‐aqueous solvents which demonstrates that cell surface wettabilities vary widely among isolates and are characterized as (i) broadly hydrophobic, (ii) broadly hydrophilic, (iii) only compatible in phases with surface tensions < 20 mN m‐1, or (iv) only compatible in phases with surface tension > 27 mN m‐1. Partitioning patterns of cultured isolates are consistent with field observations of denser colonization of low and high γcrit surfaces. The results support the hypothesis that substratum surface properties influence conditioning film attributes and continue to exert control over bacterial adsorption and attachment even after conditioning films are established.