PT  - JOURNAL ARTICLE
AU  - Chen, Yun
AU  - Harapanahalli, Akshay K.
AU  - Busscher, Henk J.
AU  - Norde, Willem
AU  - van der Mei, Henny C.
TI  - Nanoscale Cell Wall Deformation Impacts Long-Range Bacterial Adhesion Forces on Surfaces
AID  - 10.1128/AEM.02745-13
DP  - 2014 Jan 15
TA  - Applied and Environmental Microbiology
PG  - 637--643
VI  - 80
IP  - 2
4099  - http://aem.asm.org/content/80/2/637.short
4100  - http://aem.asm.org/content/80/2/637.full
SO  - Appl. Environ. Microbiol.2014 Jan 15; 80
AB  - Adhesion of bacteria occurs on virtually all natural and synthetic surfaces and is crucial for their survival. Once they are adhering, bacteria start growing and form a biofilm, in which they are protected against environmental attacks. Bacterial adhesion to surfaces is mediated by a combination of different short- and long-range forces. Here we present a new atomic force microscopy (AFM)-based method to derive long-range bacterial adhesion forces from the dependence of bacterial adhesion forces on the loading force, as applied during the use of AFM. The long-range adhesion forces of wild-type Staphylococcus aureus parent strains (0.5 and 0.8 nN) amounted to only one-third of these forces measured for their more deformable isogenic Δpbp4 mutants that were deficient in peptidoglycan cross-linking. The measured long-range Lifshitz-Van der Waals adhesion forces matched those calculated from published Hamaker constants, provided that a 40% ellipsoidal deformation of the bacterial cell wall was assumed for the Δpbp4 mutants. Direct imaging of adhering staphylococci using the AFM peak force-quantitative nanomechanical property mapping imaging mode confirmed a height reduction due to deformation in the Δpbp4 mutants of 100 to 200 nm. Across naturally occurring bacterial strains, long-range forces do not vary to the extent observed here for the Δpbp4 mutants. Importantly, however, extrapolating from the results of this study, it can be concluded that long-range bacterial adhesion forces are determined not only by the composition and structure of the bacterial cell surface but also by a hitherto neglected, small deformation of the bacterial cell wall, facilitating an increase in contact area and, therewith, in adhesion force.