Key role of <i>Desulfobacteraceae</i> in C/S cycles of marine sediments is based on congeneric catabolic-regulatory networks.

Abstract

Marine sediments are highly bioactive habitats, where sulfate-reducing bacteria contribute substantially to seabed carbon cycling by oxidizing ~77 Tmol C_org year^-1. This remarkable activity is largely attributable to the deltaproteobacterial family <i>Desulfobacteraceae</i> of complete oxidizers (to CO₂), which our biogeography focused meta-analysis verified as cosmopolitan. However, the catabolic/regulatory networks underlying this ecophysiological feat at the thermodynamic limit are essentially unknown. Integrating cultivation-based (80 conditions) proteogenomics of six representative <i>Desulfobacteraceae</i> spp., we identify molecular commonalities explaining the family's environmental relevance and success. <i>Desulfobacteraceae</i> genomes are specifically enriched in substrate uptake, degradation capacities, and regulatory functions including fine-tuned sulfate uptake. Conserved gene arrangements and shared regulatory patterns translate into strikingly similar (sub-)proteome profiles. From 319 proteins, we constructed a meta-network for catabolizing 35 substrates. Therefrom, we defined a <i>Desulfobacteraceae</i> characteristic gene subset, which we found prevalent in metagenomes of organic-rich, marine sediments. These genes are promising targets to advance our mechanistic understanding of <i>Desulfobacteraceae</i>-driven biogeochemical processes in marine sediments and beyond.