In the present study,a novel bacterium (Marinobacter aquaeolei) was examined for its corrosion inhibiting behaviour against X80 pipeline steel.Electrochemical results showed that X80 steel immersed in the solution inoculated with M.aquaeolei possessed very high corrosion resistance compared to that of abiotic control.Besides,scanning electron microscopy,confocal laser scanning microscopy and energy-dispersive X-ray spectroscopy were employed to analyse the corrosion product and the biofilm formed on the metal surface.Fourier-transform infrared spectroscopy was also applied to determine the composition of extracellular polymeric substances (EPS).Above results indicated that the corrosion inhibition efficiency observed in biotic medium was very high (91％),proving that M.aquaeolei was an effective inhibitive agent for the corrosion of carbon steel.The inhibition was credited to the formation of bacterial biofilm and the compact protective layer of the secreted EPS.Thus,this study will introduce a natural,environmentally friendly and cost-effective system for the corrosion control of the carbon steel.