Theoretical effect of cedar wood surface roughness on the adhesion of conidia from Penicillium expansum

The influence of surface topography on microbial adhesion is an important regulatory issue. In this study, we use the potential adhesion of conidia from Penicillium expansum to cedar wood as a theoretical model to understand the effect of a roughness on physico-chemical attributes of spores, and their potential adhesive properties. The effect of roughness level ranging from 1.83 to 0.45 mu m was investigated. Hydrophobicity, electron donor and acceptor character of the substrates was determined using contact angle measurements. Spore behavior switched from hydrophobic (99.2A degrees), at an Ra value of 1.83 mu m, to hydrophilic (60.02A degrees), at an Ra value of 0.45 mu m. It was difficult to find a relationship between the acid-base component of wood substrate and surface roughness over the range of Ra values tested. Prediction of the attachment tendencies of Penicillium expansum, was modeled using wood surfaces with different degrees of roughness according to the XDLVO approach. Maximum adhesion was predicted to occur at an Ra value of 1.83 mu m. However, for Ra values less than 0.75 mu m, the value of total interaction energy ranged from +4.17 mJ/m(2) (Ra = 0.6 mu m) to +6.58 mJ/m(2) (Ra = 0.45 mu m).