Adhesion ofstreptococcus thermophilus tostainless steel with different surface topography and roughness

Adhesion of Streptococcus thermophilus to AISI 304 stainless steel was studied with regard to surface topography and roughness and surface hydrophobicity. Different finishes of stainless steel were used, viz. industrial surfaces 2R and 2B and polished surfaces 3, 5 and 8. A surface tracing instrument with low resolution was not the most suitable technique to characterise solid surfaces for bacterial adhesion studies. Surface roughnesses measurements varied from 0.01 to 1 μm. The surfaces were hydrophobic initially. The number of bacteria (N) adhering to the stainless steel surfaces did not vary significantly (log N varied from 5.2 to 5.7). Three cycles of bacterial adhesion followed by a cleaning treatment were applied to the different stainless finishes. After the third cycle, bacterial clumping was observed on stainless steel surfaces. The reasons for this observation are discussed.