Aeolian Dispersal of Bacteria Associated With Desert Dust and Anthropogenic Particles Over Continental and Oceanic Surfaces

Aeolian dust is emerging as a significant vehicle for long-range transport of microorganisms. Nonetheless, many factors relating to this highly influential dispersal mechanisms remain unresolved, including the variation in dispersal bacterial communities during stochastic desert dust events, and the effect of aeolian transit over continental and oceanic surfaces to these communities. Here we report a temporal study that encompassed multiple dust events to elucidate 16S rRNA gene-defined changes in airborne bacterial communities at a continental-peninsula site (Yongin, central South Korea) and a downwind offshore island site (Yonago, Honshu Island, Japan) both lying along the trajectory for dust event transport. Aerosol collected on nondust days at both sites generally reflected local origin from freshwater, marine, plant, and animal sources. At both sites, the relative abundance of spore-forming bacteria (Bacillaceae) and organic-aggregating bacteria (Cytophagaceae) was positively correlated with the mineral particle. Actinobacteria increased in relative abundance at the continental-peninsula site during dust events, while marine bacterial signatures (mainly Alphaproteobacteria) were more prevalent in island site after dust events dissipated upon Japanese Sea. Overall, dust events increased the richness of airborne bacteria communities originating from inland desert and other area during early spring and are associated with more variations in airborne bacteria in the island site than the continental-peninsula site. Airborne desert dust is likely a significant transport vehicle for bacteria. The transit of air masses over continental and marine surfaces is selective for some taxa which can be transported to distant sinks with potential impacts toward ecosystems and public health. Plain Language Summary This is the first long-term study for demonstrating microbial transport from desert storms, at the continent-to-island scale. The high throughput approach provides robust support for the key findings: (a) the diversities of airborne bacteria increased with dust dispersals from Chinese desert to the Japanese coast; (b) bacterial taxa include markers associated with desert microbial communities as well as human and plant pathogens were detected; and (c) transit over oceanic waters and anthropogenic polluted areas strongly selects for airborne bacterial populations through atmospheric stressors. These findings have broad relevance to understanding the drivers of global microbial biogeography. The issue of large range microbial transport has a wide-ranging appeal in several areas including microbial ecology, oceanography (ocean-atmospheric interactions), and public health (epidemiology of pathogens).