Cardon, Z. G. | Search bioRxiv

bioRxiv2026

Latitudinal diversity gradients and selective microbialexchange at the Atlantic ocean-air interface

Microbial communities at the ocean-atmosphere interface play a vital role in nutrient, aerosol, and water cycling, yet their large-scale biogeography remains scarcely studied. Here we assessed microbial cell abundance and community structure in air and surface ocean samples along a 14,400 km transect from the polar circle to the equator. Air and surface ocean microbiomes were taxonomically distinct across the North East Atlantic. The microbiome in the air had a lower local community richness compared to the surface ocean, yet was more diverse across larger geographical scales. Our results suggest that terrestrial-derived air masses affected air and surface ocean communities. Air microbial communities showed a latitudinal diversity gradient with richness and cell abundance increasing from the polar circle to the equator. We observed an exchange of microbial lineages between ocean and air, however, most lineages were confined to one realm, suggesting lineage-selective aerosolization and deposition of microbial cells.

microbiology↗

bioRxiv2025

Microbial consortia in salt marsh sediments are sequentially buried over millennia and genomic complementarity analysis indicates an important role in complex carbon decomposition

Salt marsh sediments contain high levels of microbial diversity and function that reflect the heterogeneity of available nutrients, dynamic hydrology, and layers of organic matter developed over millennia. However, the microbially mediated processes involved in the cycling of complex carbon in these sediments are still largely undescribed. We used genome reconstruction, cooccurrence networks, and genome scale metabolic modeling to identify the functional capacity for organic matter decomposition among cooccurring microbes from 240 cm of sediment in a Spartina patens dominated salt marsh, representing over 3000 years of sediment accumulation. Microbial communities were structured according to depth, and the network identified significant positive cooccurrence within the community. We identified an active subnetwork of cooccurring subsurface metagenomic assembled genomes (MAGs) capable of decomposing complex carbon and aromatics. The Wood-Ljungdahl pathway was central to most of the MAGs within the subnetwork and metabolism of aromatics was potentially enabled through metabolic handoffs and the Benzoyl-CoA pathway. Variant analysis indicates that these subsurface populations are stratified with depth, suggesting high selection coupled with spatial isolation. These results provide evidence of microbial populations that persist under energy limited conditions and contribute to the transformation of organic matter within salt marsh sediment.

ecology↗