X-ray photoelectron spectroscopy for the study of microbial cell surfaces

X-ray photoelectron spectroscopy (XPS) is well known for the characterisation of material surfaces, but at first glance, is an unexpected technique to study the composition of microbial cell surfaces. Despite the fact that intimate contact between materials and microbial cell surfaces occurs in many situations, such as on oil-platforms, in water pipelines and bioreactors or on biomedical implants, XPS studies on the composition of microbial cell surfaces are less known, but equally relevant. In this review, microbial sample preparations are discussed, as well as relationships between microbial compositions using XPS. Biochemical and physical properties, such as microbial cell surface charge and hydrophobicity are also discussed. A reference guide, giving the overall cell surface composition of 210 strains determined by XPS, as collected from the literature is given. Hierarchical cluster analysis on these data reveals interesting new insights on staphylococcal cell surfaces, as well as a distinction between staphylococci, yeasts and other microorganisms. It is concluded that XPS on microbial cell surfaces yields useful information, complementing other biochemical and physical cell surface characterisations.