Retention of bacteria on a substratum surface with micro-patterned hydrophobicity

Bacteria adhere to almost any surface, despite continuing arguments about t he importance of physico-chemical properties of substratum surfaces, such a s hydrophobicity and charge in biofilm formation. Nevertheless, in vivo bio film formation on teeth and also on voice prostheses in laryngectomized pat ients is less on hydrophobic than on hydrophilic surfaces. With the aid of micro-patterned surfaces consisting of 10-mu m wide hydrophobic lines separ ated by 20-mu m wide hydrophilic spacings, we demonstrate here, For the fir st time in one and the same experiment, that bacteria do not have a strong preference for adhesion to hydrophobic or hydrophilic surfaces. Upon challe nging the adhering bacteria, after deposition in a parallel plate flow cham ber, with a high detachment force, however, bacteria were easily wiped-off hydrophobic lines, most notably when these lines were oriented parallel to the direction of flow. Adhering bacteria detached slightly less from the hy drophilic spacings in between, but preferentially accumulated adhering on t he hydrophilic regions close to the interface between the hydrophilic spaci ngs and hydrophobic lines. It is concluded that substratum hydrophobicity i s a major determinant of bacterial retention while it hardly influences bac terial adhesion. (C) 2000 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.