Aerial transport of bacteria by dust plumes in the Eastern Mediterranean revealed by complementary rRNA/rRNA-gene sequencing

Abstract

Processes influencing the transport of airborne bacterial communities in the atmosphere are poorly understood. Here, we report comprehensive and quantitative evidence of the key factors influencing the transport of airborne bacterial communities by dust plumes in the Eastern Mediterranean. We extracted DNA and RNA from size-resolved aerosols sampled from air masses of different origins, followed by qPCR and high-throughput amplicon sequencing of 16 S ribosomal RNA gene and transcripts. We find that airborne bacterial community composition varied with air mass origin and particle size. Bacterial abundance, alpha diversity and species richness were higher in terrestrially influenced air masses than in marine-influenced air masses and higher in the coarse particle fraction (3.0 to 10.0 µm) than in the fine fraction (0.49 to 1.5 µm). This suggests that airborne bacteria mainly were associated with dust particles or transported as cell aggregates. High abundances of rRNA from human, animal and plant pathogen taxa indicate potential ecological impacts of atmospheric bacterial transport.

Environmental processes and health implications potentially mediated by dust‐borne bacteria

“…Notably, DE‐II displayed significant day/night wind speed differences (7.78 m/s vs. 3.38 m/s, respectively). Wind speed has been previously linked with dust generation and bacteria transportation (Erkorkmaz et al, 2023 ; Fujiyoshi et al, 2017 ; Sorkheh et al, 2022 ; Ulrich, 2021 ), possibly associated with the observed microbial richness variation during this event, showing higher values for the daytime samples (see Table 1 , Chao1 and abundance‐based coverage estimator [ACE] values).…”

“…The particulate load has been linked with an increase in microbial richness (Erkorkmaz et al, 2023 ). A similar pattern was observed in our study, showing positive relations between higher PM concentrations (observed in DE_II and DE_III) and richness parameters (Chao1 and ACE values; Table 1 ).…”

“…Moreover, they can significantly impact aquatic, atmospheric, and terrestrial environments and human health (Lang‐Yona et al, 2020 ; Maki et al, 2022 ; Risely et al, 2018 ; Sadakane et al, 2022 ). Extensive research has focused on dust‐borne microbial diversity including bacteria, eukaryotes, archaea and viruses (Aalismail et al, 2019 ), with the majority being the bacterial group, with predominance of Actinobacteriota, Bacteroidota, Firmicutes and Proteobacteria (Aalismail et al, 2019 ; Elmassry et al, 2020 ; Erkorkmaz et al, 2023 ; Gat et al, 2021 ). Bacillus species were detected in Asian dust events (DEs) and several East Asian countries (An et al, 2013 ; Maki et al, 2014 ), and are known for spore‐forming, which provides protection and enables long‐distance atmospheric transport (An et al, 2013 ; Griffin, 2004 ; Wainwright et al, 2003 ).…”

“…Distinguishing between active and inactive microbes offers meaningful ecological insights into microbial survival strategies and their interactions with the dust environment (Schuerger et al, 2018 ). A few studies have utilized ribosomal RNA (rRNA) sequencing to characterize the potentially active airborne bacterial community (Blazewicz et al, 2013 ; Erkorkmaz et al, 2023 ; Šantl‐Temkiv et al, 2018 ), focusing primarily on the transcriptionally active microbial community structure and their relation to environmental factors such as air mass origination, atmospheric particulate matter (PM; <10 μm; PM10), and particle‐size (Erkorkmaz et al, 2023 ). However, the potential relation to meteorological parameters, diurnal changes, and the possible interaction mechanism and functionality within dust‐borne microbial communities remained elusive.…”

Atmospheric ice-nucleating particles in the Eastern Mediterranean and the potential influence of fertile soils

“…Israel has varying airborne microbiomes that depend on air mass, and Gat et al (Gat et al, 2017;Gat et al, 2021;Erkorkmaz et al, 2023;Peng et al, 2021) have measured a variety of desert-and soil-associated bacteria and fungi in air masses that passed over the Nile Delta and the Arabian Peninsula, with some of the latter cases also containing agricultural soil bacteria. Samples from days with no dust events mostly contained bacteria assoc iated with human activity.…”