ADHESIVE EXTRACELLULAR POLYMERS OF HYPHOMONAS MHS-3 - INTERACTION OF POLYSACCHARIDES AND PROTEINS

The adsorption behavior of extracellular polymeric substances (EPS) fr om the marine bacterium Hyphomonas MHS-3 was investigated using attenu ated total reflection Fourier transform infrared (ATR/FT-IR) spectrome try. The protein fraction of the crude EPS (EPS(c)) (propanol precipit ated/extracted with EDTA) dominated the adsorption onto the germanium substratum Removal of the Protease K accessible portion of the EPS(c) protein, and treatment with RNase and DNase, yielded a hygroscopic sub stance (EPS(p)) which contained at least one adhesive polysaccharide c omponent. Conditioning the substratum with EPS(c) diminished adsorptio n of the polysaccharide fractions in EPS(p); pre-adsorbed EPS, protein was nor displaced. The rate of EPS(c) adsorption on substrata conditi oned with EPS(p) was slower than to clean germanium; however, the proj ected surface coverage of protein after long times, based on an empiri cal datafit, was the same as that for a clean substratum; the EPS(c) p roteins did nor displace the pre-adsorbed adhesive polysaccharide frac tion. SDS-PAGE (Coomassie blue stain) revealed an extensive homology b etween proteins from cell lysates and EPS(c) proteins. However, distin ct differences in the banding pattern suggested that proteins did not originate primarily from cell lysis during tile extraction procedure. The results indicate that adhesive components of EPS, with respect to a hydrophilic surface (germanium), can be either protein or polysaccha ride and that they may compete for interfacial binding sites.