Abstract
Bacterial adhesion to silica sand was related to variations in system Gibbs energy Δ G adh. Two typical Gram-positive bacterial strains of Streptococcus mitis and Lactobacillus casei were used as the model bacteria in this research. Impacts of solution chemistry and goethite coating of silica sand on bacterial adhesion were also explored. S. mitis and L. casei had negative Δ G adh with both uncoated and goethite-coated silica sand, demonstrating their adhesion potentials to these substrate. After goethite coating, Δ G adh decreased (negatively increased) for both S. mitis and L. casei. In the presence of rhamnolipid biosurfactant, Δ G adh increased (negatively decreased) in answer to the increase of the rhamnolipid biosurfactant concentration. Bacterial percentage adhesion to silica sand corresponded to Δ G adh. This study demonstrated that bacterial adhesion to substrate could be explained in terms of bacterial, substratum and intervening medium physicochemical surface properties, which can be independently determined based on contact angle measurements.
Published Version
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