The transient and species-specific microbiome of radiation fog water

We used sampling of quasi-stagnant radiation fogs in Central Pennsylvania during two years to study the dynamics and microbiology of bacterial assemblages in fog droplets. These microbiomes contain concentrations of bacteria orders of magnitude higher than present in concurrent interstitial aerosols, their concentration depending positively, and unlike chemical solutes, on the fog’s liquid water content and temperature, speaking for the role of in situ growth. Fog water microbiomes are recruited from locally available aerosol bacteria, they are compositionally well-differentiated, and their bacteria display differential cellular traits consistent with an actively growing assemblage. Phylogenetic analyses of bacteria enriched in the droplets suggest that C1-volatile metabolizing heterotrophs constitute the trophic basis of these dynamics. However, major loss factors (wet deposition) export much of the net gains, leaving measurable but only subtle legacies in the aerobiome upon fog dissipation.