Adhesion of Pseudomonas aeruginosa and its effects on the physicochemical properties of 304 stainless steel immersed in artificial seawater

Pseudomonas aeruginosa is a pioneer bacterium that can initiate biofilm formation in a seawater environment, causing biofouling and biocorrosion. Therefore, understanding the interactions that occur between this bacterium and a commonly used material, 304 stainless steel, in the marine environment is mandatory before attempting to identify methods that can mitigate biofilm development. Thus, in this study, we investigated in one hand the adhesion potential of P. aeruginosa to sea-immersed 304 stainless steel using thermodynamic approach and the Environmental Scanning Electron Microscopy (ESEM) and in the other hand, the effect of the adhesion on the physicochemical characteristics of the stainless steel surface. The contact angle measurements showed that the bacterium has a hydrophilic character, with θw = 9.5 ± 0.4° and ΔGiwi = 20.88 mJ·m−2, a strong electron-donor character, with γ− = 52.5 ± 0.2 mJ·m−2, and a weak electron-acceptor character, with γ+ = 7.14 ± 0.1 mJ·m−2. For the substrate surface, we found that sea-immersed 304 stainless steel was hydrophilic and presented a strong electron-donor character and a weak electron-acceptor character. The theoretical prediction showed that the strain exhibited positive value of ΔGXDLVO vis-a-vis the sea-immersed stainless steel which indicates unfavorable adhesion while the ESEM electro-micrograph showed that the bacterium was able to adhere to sea-immersed 304 stainless steel. Furthermore, the results revealed that the physico-chemical properties of the sea-immersed 304 stainless steel surface changed significantly following the bacterial adhesion.