Kinetics of conditioning layer formation on stainless steel immersed in seawater

Adhesion of microorganisms to surfaces in marine environments leads to biofouling. The deleterious effects of biofilm growth in the marine environment are numerous and include energy losses due to increased fluid frictional resistance or to increased heat transfer resistance, the risk of corrosion induced by microorganisms, loss of optical properties, and quality control and safety problems. Antifouling agents are generally used to protect surfaces from such a biofilm. These agents are toxic and can be persistent, causing harmful environmental and ecological effects. Moreover, the use of biocides and regular cleaning considerably increase the maintenance costs of marine industries. An improved knowledge of biofilm adhesion mechanisms is needed for the development of an alternative approach to the currently used antifouling agents. The aim of this study is to characterise the chemical composition of the molecules first interacting with stainless steel during the period immediately following immersion in natural seawater and to elucidate the kinetics of the adsorbtion process. Proteins are shown to adhere very rapidly, closely followed by carbohydrates. The distribution on the surface of organic molecules is also examined. The adsorbate on the surface is not a continuous film but a heterogeneous deposit, whose average thickness varies widely. The cleaning procedures used affect the adsorption kinetics. In particular, cleaning with hexane results in slower adsorption of nitrogen-containing species than does cleaning in acetone

Ann. microbiol.

Purpose Brettanomyces bruxellensis is a serious source of concern for winemakers. The production of volatile phenols by the yeast species confers to wine unpleasant sensory characteristics which are unacceptable by the consumers and inevitably provoke economic loss for the wine industry. This ubiquitous yeast is able to adapt to all winemaking steps and to withstand various environmental conditions. Moreover, the ability of B. bruxellensis to adhere and colonize inert materials can be the cause of the yeast persistence in the cellars and thus recurrent wine spoilage. We therefore investigated the surface properties, biofilm formation capacity, and the factors which may affect the attachment of the yeast cells to surfaces with eight strains representative of the genetic diversity of the species.[br/] Methods The eight strains of B. bruxellensis were isolated from different geographical and industrial fermentation origins. The cells were grown in synthetic YPD medium containing 1% (w/v) yeast extract (Difco Laboratories, Detroit), 2% (w/v) bacto peptone (Difco), and 1% (w/v) glucose. Surface physicochemical properties as electrophoretic mobility and adhesion to hydrocarbon of the cells were studied. The ability of the strains to form biofilm was quantified using a colorimetric microtiter 96-well polystyrene plate. Biochemical characteristics were examined by colorimetric methods as well as by chemical analysis.[br/] Result Our results show that the biofilm formation ability is strain-dependent and suggest a possible link between the physicochemical properties of the studied strains and their corresponding genetic group.[br/] Conclusion The capacity to detect and identify the strains of the spoilage yeast based on their biofilm formation abilities may help to develop more efficient cleaning procedures and preventing methods