A novel procedure for the quantitative analysis of biofilm formation by bacteria and yeasts, the Plate-hanging method, was developed. In this system, various polymer disks were hung from the lid of a 6-well plate, immersed in a cell suspension, and moderately shaken (70 rpm). In order to verify the validity of the procedure, the effects of the solid surface hydrophobicity of the test disks and the cell surface hydrophobicities of microorganisms on biofilm formation were investigated. Biofilm formation of bacteria and yeasts on the solid surface strongly depended on hydrophobic interactions between the solid surface and the cell surface. A positive correlation between the hydrophobic properties of substratum and cell surfaces was observed. On the other hand, hydrophilic yeasts preferentially adsorbed onto relatively hydrophilic surfaces. Moreover, the plate-hanging method coupled with the periodic exchange of the liquid medium enabled the quantification of long-term biofilm growth.
Keywords: Biofilm; Cell surface hydrophobicity; Microbial adhesion; Plate-hanging method; Solid surface hydrophobicity.
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