| Summary: | Sulfate-reducing bacteria (SRB) and iron-oxidizing bacteria (IOB) are one of the typical representatives of anaerobic and aerobic bacteria, which can form a synergistic community (mixed species biofilm) on the surface of material. In this work, the corrosion behavior of X65 steel in seawater containing SRB and IOB was investigated with electrochemical impedance spectroscopy, potentiodynamic polarization, scanning electron microscopy, energy dispersive spectroscopy and X-ray photoelectron spectroscopy. Results showed that the combination of anaerobic SRB and aerobic IOB affected the corrosion behavior of X65 steel greatly, and the corrosion rate was higher than that in single SRB or IOB medium. The corrosion mechanisms of X65 steel in mixed SRB and IOB could be divided into three stages, which were controlled by the metabolic activities of bacteria (SRB and IOB), biofilm structure and metabolic products comprehensively. Keywords: Sulfate-reducing bacteria, Iron-oxidizing bacteria, Microbiologically influenced corrosion, Biofilm, Metabolic products
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