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 in the biotic reactor for as received (AR) and polished (P) coupons respectively. There was an average pit density of 3 pits mm 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.