Surface hydrophobicity of particles and bacteria in Melbourne's water storage system

An important parameter in describing bacterial adhesion to particles -- hydrophobicity -- has been investigated for bacteria and particles found within Melbourne’s water storage system. Data was obtained using two commonly-employed methods: contact angle measurement (CAM) and the adhesion to hydrocarbon (ATH) assay. The adhesion to hexadecane of particles collected from Silvan reservoir was found to decrease significantly when organic matter was removed from their surface by oxidation, although contact angle was not as significantly affected. The rate of conditioning film (CF) deposition was also determined, with exposure of glass slides to filtered water resulting in an increased contact angle. For the bacterial strains studied, interfacial surface tension and surface free energy parameters were calculated, thereby allowing hydrophobicity to be quantified. Change in adhesion to hexadecane of bacteria exposed to starvation conditions for two weeks was also investigated.