Bacterial stress adaptation and antibiotic resistance in dust-transportable bioaerosols originating from the Gobi Desert

Abstract

Airborne microorganisms which dispersed from the Gobi Desert throughout East Asia via long-range dust transports, are believed to maintain their viability against atmospheric stressors that influence ecosystem dynamics and human health during deposition in downwind environments. However, the adaptative mechanisms that facilitate microbial tolerance to environmental stressor, and the persistence of factors such as antibiotic resistance relevant to human health have not been determined. Here, we described the metagenomic and physiological interrogation of airborne bacteria collected from aerosols at an altitude of 500 m using a balloon-mounted sampler and at a parallel site 3 m above the ground in the dust-source region of Gobi Desert. The shotgun metagenomic DNA sequencing which determine was performed for characterizing the taxonomic compositions of airborne bacteria and their potential functions. The communities were dominated by species in the phyla Actinobacteria, Bacillota, Bacteroidota, and Pseudomonadota (Alpha). Metabolic-pathway analysis revealed that Gobi Desert bioaerosols were enriched in functions associated with antibiotic resistance, cell-membrane transporters, and/or environmental adaptation. The antibiotic and osmotic-change resistances were confirmed among viable bacteria isolates showing higher level of resistances in the aerosols collected at 500 m than those of 3 m. These findings suggest that elevated altitudes result in environmental filtering that allows bacterial taxa to survive long-term transport to distant locations during dust events and transfer antibiotic resistance.

Keywords: Airborne bacteria; Asian dust source; Bioaerosol; High altitude.