Metabolic strategies of sulfate-reducing microorganisms under energy-limited conditions in oil reservoirs

Abstract

Sulfate-reducing microorganisms (SRMs, including both bacteria and archaea taxa) drive bio-corrosion and bio-souring in oil reservoirs. However, the adaptation strategies of SRMs to energy-limited conditions, induced by nutrient competition and metabolic inhibition, challenge the prolonged effectiveness of traditional control strategies. This study provides a comprehensive genomic synthesis of the metabolic strategies employed by SRMs under such constraints to sustain energy metabolism and intracellular redox balance. A total of 752 metagenome-assembled genomes (MAGs) from eight oil reservoir blocks were reconstructed and 60 SRM genomes were identified. Phylogenetic and functional analyses revealed pronounced metabolic heterogeneity between oxidative and reductive DsrAB lineages. Beyond canonical sulfate reduction, SRMs encode a diverse array of sulfur–sulfur bond–cleaving enzymes and hydrogenases, which contribute to redox balancing and energy conservation under energy-limited conditions. Furthermore, the widespread presence of conductive structures including pili and outer-membrane multiheme cytochromes encoded within uncultured SRMs suggests a significant potential for direct or flavin-mediated interspecies electron transfer. Collectively, these findings propose a mechanistic framework for understanding SRM resilience under the energy-limited conditions. These genomic insights also advance the fundamental basis for developing targeted strategies for bio-corrosion and bio-souring control.