Clostridium in the ambient air: a study on the diversity of species using size-fractionated sampling and culture methods at a suburban site in central Japan

The aim of this study was to isolate culturable outdoor airborne Clostridium spp. and clarify their size distribution, diversity, and possession of virulence and antibiotic resistance genes (ARGs). In a suburban site of Toyama City in central Japan, we conducted 39 ambient aerosol sampling campaigns with size-fractionated samplers over a two-year period. From the collected samples, the isolation of culturable Clostridium spp. was performed, and whole-genome sequencing (WGS) were carried out. Genomic analyses were conducted to find the phylogenetic position and examine the presence of virulence and antibiotic resistance genes for all the isolates. The bacterial communities in aerosol samples were also investigated using amplicon sequencing to examine Clostridium spp. in the communities.