Quantification of Bacillus subtilis and Bacillus sp. Adhesion on Fez Medina Cedar Wood

Abstract

The adhesion of Bacillus subtilis and Bacillus sp. isolated from Fez cedar wood decay has been investigated. Furthermore, the physicochemical proprieties including hydrophobicity and electron donor/electron acceptor (Lewis acid–base) of both bacteria and substrata were evaluated using contact angle measurements. The results show that Bacillus subtilis has a hydrophobic character (ΔG iwi = –20 mJ/m2). In contrast, Bacillus sp. exhibits a hydrophilic (ΔG iwi = –20 mJ/m2), electron donating (γ–) and weakly electron accepting (γ+) character. With respect to the substrata surface, we found that the cedar wood used in this work, was hydrophobic in character, having relatively more electron-donor that electron-acceptor properties (γ– = 6 ± 4 mJ/m2; γ+ = 0 ± 3 mJ/m2). The phenomena of adhesion were observed by environmental scanning electron microscopy (ESEM) and cell adhesion was quantified using a Matlab program. The analysis of images obtained by ESEM show that the both cells was able to adhere to the wood substrata and the quantitative adhesion results showed that the surface coverage by Bacillus sp. (90%) was higher than that by the Bacillus subtilis strain (40%).