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Bacterial fouling of reverse osmosis (RO) membranes contributes to reduction of energy efficiency of the reverse osmosis process. This article describes an investigation conducted at Water Factory 21 to clarify the fundamental mechanism of the mycobacterial adhesion process and to learn more about the attractive forces that exist between the bacterial cell surface and the reverse osmosis membrane. Adhesion of a Mycobacterium sp. previously isolated from an early stage of RO membrane biofouling was relatively unaffected by large variations in the ionic strength or pH of the buffer system. However, trace quantities of a polyoxyethylene ether nonionic detergent almost completely inhibited attachment. The mycobacteria were found to adhere to the cellulose acetate (CA) membrane surface (or to a CA-affinity column) approximately 25-fold more effectively than a wild-type strain of Escherichia coli. The ability of Mycobacterium and E. coli to adhere to the membrane was correlated with their relative surface hydrophobicities as determined by their affinities for n-hexadecane. A similar correlation was established between a hydrophilic wild-type strain of Acinetobacter phosphadevorus containing a single 17.8 megaDalton plasmid (PYG1) and a more hydrophobic isogenic derivative strain (P7P-) lacking the PYG1 plasmid. Unlike the P7WT parent strain, the P7Pderivative produced more fimbrialike appendages, which may account for its enhanced hydrophobic and adhesive properties. The results suggest that hydrophobic interactions between bacterial cell surface components and the CA membrane surface play an important role in the initial stages of bacterial adhesion and RO membrane biofilm formation. Includes 36 references, table, figures.

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Edition: Vol. 77 - No. 7 Published: 07/01/1985 Number of Pages: 10 File Size: 1 file , 3 MB