From laminar to turbulent: how methanogen and srb mic pathways shape their response to flow dynamics

Abstract Hydrodynamic conditions play a central role in microbiologically influenced corrosion (MIC) by regulating nutrient transport, metabolite removal, shear stress, and biofilm stability. As industrial systems operate across laminar and turbulent flow regimes, understanding MIC under controlled hydrodynamics is essential. In this study, the corrosion behavior of carbon steel was examined in the presence of Methanobacterium aff. IM1 and Desulfovibrio ferrophilus IS5 under laminar and turbulent flow. Corrosion rates were quantified by weight loss, and surface morphology was characterized using microscopy and tomography. Flow regime significantly influenced corrosion behavior for both microorganisms. Turbulent flow increased corrosion rates compared to laminar and abiotic controls, with Methanobacterium aff. IM1 exhibiting the highest overall corrosivity. Biotic conditions promoted more severe localized corrosion, with the deepest and widest pits observed for Methanobacterium aff. IM1. Under turbulent flow, Desulfovibrio ferrophilus IS5 developed significantly thicker and more heterogeneous biofilm–corrosion layers, whereas Methanobacterium aff. IM1 exhibited corrosion layers of comparable thickness to abiotic samples but with markedly increased surface roughness. These results demonstrate that biofilm thickness alone does not reflect corrosion severity and identify hydrodynamic regime as a key driver of MIC intensity and morphology.