Preemptive biofilm colonization blocks microbial metal corrosion

Sustainable materials are needed to address the serious economic and safety risks of microbial metal corrosion. Colonizing metal surfaces with biofilms of noncorrosive microbes was previously shown to reduce aerobic, abiotic corrosion. However, the ability of biofilms to thwart highly corrosive anaerobic microbes is untested. Here we report on a strain of Escherichia coli genetically modified for enhanced metal adherence and adaptively evolved to tolerate sulfide. The E. coli biofilms effectively inhibited all known major routes for anaerobic microbial iron corrosion, including proton and sulfide attack, as well as the highly aggressive corrosion of electroactive microbes that directly extract electrons from Fe⁰. The E. coli biofilms prevented corrosion much better than biofilms of other microorganisms previously reported to reduce aerobic, abiotic corrosion. The results highlight the possibility of tailoring biofilm properties to function as effective sustainable, self-healing coatings to safeguard critical metal infrastructure.