Abstract
Marine fouling development upon stainless steel and elastomeric surfaces was studied by light and electron microscopy and the observed contributions of the various organisms involved is discussed. As an extension of the above, the bacteriology of a mature fouling film from stainless steel was examined. Characterized isolates were classified by numerical taxonomy. Species of Vibrio dominated the isolatable aerobic heterotrophic bacterial community. A number of previously undescribed species were discovered, highlighting inadequacies of current identification schemes. Isolate characteristics are discussed in relation to conditions during fouling development. Immuno- location of species within TEM sections of fouling was attempted without success. Macromolecular dissolved organic materials were isolated from seawater by ultrafiltration, and characterization showed these materials to be humic substances, predominantly fulvic acid. Concentrated solutions of these materials were used to organically pretreat stainless steel surfaces prior to marine immersion, and the fouling of these and clean surfaces was compared. It was discovered that preadsorbed material can influence both the in vivo attachment and growth of microorganisms and subsequent fouling succession. Natural molecular fouling was also studied in relation to bacterial attachment. In vitro assessment of the attachment of a marine Vibrio Sp. to pretreated and clean stainless steel after prior growth in the presence of different concentrations of different macromolecular species revealed a relationship between growth regime and adhesive tendancy. The effect of humic materials on the growth of selected bacteria was investigated in vitro. Some isolates grew with these materials acting as sole sources of carbon, nitrogen and energy. Bacterial growth on acetate was stimulated by humic materials at specific concentrations, although inhibitory effects were apparent if concentrations of the latter were increased further. The growth physiology of marine bacteria in the. presence of humic substances and the possible role of humic substances in fouling community development is discussed.