The impact of gravitational sedimentation on the sulfate-reducing bacterium biofilms formation that induced biocorrosion of X80 steel

In this study, X80 steel square specimens were immersed in a culture of sulfate-reducing bacteria (SRB), Desulfovibrio vulgaris, and the impact of gravity sedimentation on biofilm formation was investigated in three different directions (upward, sideward, and downward). A systematic investigation of biocorrosion induced by different biofilm formations during the lifespan of one D. vulgaris was illustrated using cell counts, weight loss measurements, biofilm observations, pit profiles, electrochemical tests, and X-ray diffraction (XRD). The results indicate that the gravitational field, which is an objective existence of the Earth, significantly affects the adhesion and formation of D. vulgaris biofilm, which directly determines the MIC behavior. The thickest D. vulgaris biofilm formed on the upward-facing X80 square specimens, followed by the side-facing X80 square specimens, while the thinnest and porous biofilms formed on the downward-facing X80 square specimens, induced significantly different degrees of microbiologically influenced corrosion (MIC) behaviors on the X80 steel.