Spatial and Temporal Dynamics of Chemosynthetic Microbial Biofilms at Deep-Sea Hydrothermal Vents

Deep-sea hydrothermal vents owe their extraordinary productivity to chemosynthetic microbial biofilms that colonize mineral and biological surfaces within steep redox gradients. Although Campylobacterota (formerly Epsilonproteobacteria) have long been recognized as dominant pioneers on newly exposed substrates, their ecological role in established, mature biofilms has remained unclear. A comprehensive study by Grosche et al. (Environmental Microbiome, 2025) provides the first integrated spatial, temporal, and functional analysis of active vent biofilms across the full successional continuum from days-old experimental colonizers to decades-old animal-associated communities, and from the seafloor into the shallow subseafloor. Using 16S rRNA amplicon sequencing of reverse-transcribed RNA and comparative metatranscriptomics, the authors demonstrate that Sulfurimonas and Sulfurovum universally dominate newly formed biofilms regardless of temperature, sulfide concentration, or macrofaunal host. Surprisingly, biofilm age not locality or host identity emerges as the strongest driver of community structure. Even in mature, high-diversity assemblages on mussels and tubeworms, Campylobacterota remain abundant and transcriptionally active. A rare subseafloor seafloor metatranscriptome comparison further reveals dramatic shifts in respiratory and stress-response gene expression within taxonomically similar populations. These findings establish Campylobacterota as persistent foundation species that orchestrate vent ecosystem development and resilience across space, time, and subsurface gradients, reshaping our understanding of primary succession in extreme environments.