Study of microbial adhesion on some wood species: Theoretical prediction

The initial interaction between microorganisms and substrata is mediated by physicochemical forces, which in turn originate from the physicochemical surface properties of both interacting phases. In this context, we have determined the physicochemical proprieties of all microorganisms isolated from cedar wood decay in an old monument at the Medina of Fez-Morocco. The cedar wood was also assayed in terms of hydrophobicity and electron donor-electron acceptor (acid-base) properties. Investigations of these two aspects were performed by contact angles measurements via sessile drop technique. Except Bacillus subtilis strain (Giwi < 0), all strains studied showed positive values of the degree of hydrophobicity (Giwi > 0) and can therefore be considered as hydrophilic while cedar wood revealed a hydrophobic character (Giwi = 58.81 mJ m⁻²). All microbial strains were predominantly electron donor. The results show also that all strains were weak electron acceptors. Cedar wood exhibits a weak electron donor/acceptor character. Based on the thermodynamic approach, the Lifshitz-van der Waals interaction free energy, the acid-basic interactions free energy, the total interaction free energy between the microbial cells and six different wood species (cedar, oak, beech, ash, pine and teak) in aqueous media was calculated and used to predict which microbial strains have a higher ability to adhere to wooden surfaces. Except of weak wood, for all the situations studied, generalizations concerning the adhesion of the microbiata on wood species cannot be made and the microbial adhesion on wooden substrata was dependent on wood species and microorganisms tested.