A novel model is developed to evaluate the van der Waals (vdW) interactions between a capsule shaped bacterium (P. putida) and flat minerals plates in different approach profiles: Vertically and horizontally. A comparison of the approaches to the well-developed spherical particle to mineral surface (semi-infinite wall and spherical) approach has been made in this investigation. The van der Waals (vdW) interaction potentials for a capsule-shaped bacterium are found using Hamaker's microscopic approach of sphere to plate and cylinder to plate either vertically or horizontally to the flat surface. The numerical results show that a horizontal orientated capsule shaped bacterium to mineral surface interaction was more attractive compared to a capsule shaped bacterium approaching vertically. The orientation of the bacterial approaching a surface as well as the type and topology of the mineral influence the adhesion of a bacteria to that surface. Furthermore, the density difference among each type of bacteria shape (capsule, cylinder, and sphere) require different amounts of energy to adhere to hematite and quartz surfaces.
Keywords: bacterial adhesion; capsule-shaped bacteria; pseudomonas putida; surface energy; van der Waals forces.