Free energy of adhesion of nitrifying bacteria to limestone and basalt

• Author(s): Teixeira, P. ; Azeredo, Joana ; Oliveira, Rosário
• Date: 1998
• Persistent ID: http://hdl.handle.net/1822/3591
• Origin: RepositóriUM - Universidade do Minho
• Subject(s): Adhesion; Surface properties; Thin-layer wicking; Contact angle
• Document Type: Conference Object
• Language: English

Description

Any surface in contact with a biological fluid is a potential target for microbial cell adhesion. In this process, the surface properties of both interacting bodies, like surface charge and surface free energy play an important role. Surface energy considerations enable the computation of the free energy of adhesion between two surfaces - the thermodynamic model. According to this model, bacterial adhesion will be favoured if the process itself causes the free energy to decrease, ΔG IF = ΔG LW + Δ G AB <0, where LW means Lifshitz-van der Waals interactions (apolar) and AB stands for Lewis acid-base interactions (polar). To determine the surface free energy components of a solid, contact angles of three different liquids (for which apolar and polar components are known) need to be measured. However, when the solid material is in a particulate form an alternative technique “Thin-Layer Wicking” has to be used [1]. In the present study the two methods were compared by determining the free energy of interaction between nitrifying bacteria and supporting materials (basalt and limestone) when immersed in liquid medium (Table 1).