Effects of Sulphate-Reducing Bacteria Mixed-Species Biofilms on Microbiologically Influenced Corrosion

Sulphate reducing prokaryotes are widely acknowledged as key contributors to microbiologically influenced corrosion in industry. Characterisation of their behaviour within mixed-species biofilms that reflect ecologically relevant conditions is limited. A novel dual anaerobic biofilm reactor protocol allowed a complex microbial consortium to be investigated. Continual biofilm growth resulted in significantly greater corrosive pit density, with 15 and 47 pits mm^-2 in the biotic reactor for as received (AR) and polished (P) coupons respectively. There was an average pit density of 3 pits mm^-2 in the abiotic reactor for both AR and P coupons. Moreover, a greater pit depth and size were observed when compared to the sterile abiotic conditions. Identifying and understanding the relative contributions of different microbial mechanisms within mixed-species biofilms is critical. Importantly, electroactive and corrosive Desulfovibrio desulfuricans and Desulfovibrio vulgaris were identified within the biofilm. These microorganisms play a crucial role in extracellular electron transfer, a key process in microbiologically influenced corrosion. The protocol not only deepens the mechanistic understanding of MIC but also offers a versatile tool for testing mitigation strategies under realistic and customizable conditions. This integrated approach can ultimately support the development of more targeted, sustainable corrosion prevention and management practices.