Distributing regionally, distinguishing locally: examining the underlying effects of local land use on airborne bacterial biodiversity

Abstract

Airborne bacteria are abundant and can vary with land use. Urban expansion is increasing rapidly at a global scale, altering natural sources of airborne bacterial biodiversity, as soils and native plants are replaced by pavement and managed yards. Urbanization homogenizes the biodiversity of larger organisms, but its effects are understudied with respect to microbes. This study uses categorical and gradient approaches to examine airborne bacterial communities in southwest Michigan (USA). Airborne communities carried a gut-microbial signature and were equally homogenous above urban and rural sites, despite greater homogeneity of soil communities at urban sites. Ruminococcaceae were abundant, the source of which is likely wildlife. Beyond the gut-microbial signature, there were underlying effects of land use, which were evident in the shared airborne taxa across urban and rural sites. Bacillales, Burkholderiales, Alteromonadales and Pseudomonadales were shared more across urban sites, while Xanthomonadales, which contains crop-plant pathogens, were shared across rural agricultural sites. These results suggest that taxa which may distribute globally, coupled with localized sources, contribute to urban communities, while regional rural activities drive rural composition. We determined that soils were unlikely to contribute to broad distribution of some plant-associated taxa, but may be a source for distribution of others.

Spatiotemporal Controls on the Urban Aerobiome

“…Other vegetation and meteorological variables, while significant, explained far less community variation (Table 1). Consistent with our results, other recent studies also have found airborne bacterial composition to be closely coupled with individual sampling sites (Seifried et al, 2015;Docherty et al, 2018). In contrast, several earlier culture-independent aerobiome studies found spatial location within an urban area to be insignificant compared to the effect of time (e.g., Brodie et al, 2007;Fierer et al, 2008;Bowers et al, 2013).…”

Dispersal alters soil microbial community response to drought

“…Dispersal buffered reductions in biomass under drought but also facilitated greater loss of some metabolic functions, and reduced species richness. Drought will continue to grow as a major threat to food production, and microbial dispersal rates can change with land use fragmentation (Bell and Tylianakis, 2016) but are rarely measured (but see Bowers et al, 2011;Docherty et al, 2018). Aerial dispersal could alter the response of soil communities to global change, but predicting the direction of this response will require a greater understanding of the mechanisms at play during changes in dispersal.…”

The Biogeography of Dust in the Eastern Mediterranean

“…This effort has created a growing knowledge base on the microbial community in the atmosphere and has provided a few clues regarding the variability, viability and functionality of this community. However, many questions remain unanswered; although the studies were performed at different locations around the globe (e.g., Europe and the Alps, [8][9][10] Asia, 2,11−13 the Mediterranean, 7,14 North America, 15,16 South America, 17 the Amazon rainforest, 18 and Antarctica 19 ), little is known about the residence time of microorganisms in the atmosphere; the connectivity of microbial communities between regions; the presence of a "core" microbiome in the atmosphere; anthropogenic effects on the atmospheric microbiome; and the role played by the atmosphere in the introduction of new bacteria and functions to different environments, and therefore about the global dissemination of pathogens and antibiotic resistance genes. Finally, the viability and functionality of airborne microorganisms in different niches within the atmosphere, such as clouds vs. dust storms, remain unknown.…”