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Simple Summary: Air pollution has been identified as a contributing factor to increasing antibiotic-resistant bacteria in the microbiome of dust particles. The aim of the study was to structurally and functionally characterise the microbial communities of dust particles in urban ecosystems of Moscow and to compare the prevalence of predicted resistome modules and culturable antibiotic-resistant bacteria in the microbiomes. The present study revealed a higher prevalence of antibiotic-resistant bacteria in the microbiomes of dust particles sampled in the most polluted functional zones of Moscow. Furthermore, antibiotic resistance was a more diverse functional characteristic of the microbial communities of airborne particles. Urban dust samples were collected in Moscow (Russia) in June 2021. The samples were collected in three functional zones of Moscow (traffic, residential, and recreational) and included air microparticles, leaf dust, and paved dust. Data on the taxonomic composition of bacterial communities were obtained for dust samples, and their functional characteristics were predicted using PICRUSt2 2.5.0 and FAPROTAX 1.8.0 software. The culturable part of the bacterial community was examined for the presence of antibiotic-resistant strains with respect to β-lactams, tetracyclines, amphenicols, and aminoglycosides. The presence of bacteria resistant to ceftazidime, cefepime, and tetracycline was detected in all dust samples. The presence of bacteria resistant to meropenem and amikacin was only observed in the dust collected from leaves in the residential and traffic zones. The overall abundance of cultured antibiotic-resistant bacteria from the total heterotrophs ranged from 0.03% to 1.88%, with the highest percentage observed in dust from the residential zone. Notably, strains resistant to all antibiotics tested were observed in the leaf dust bacterial community. [ABSTRACT FROM AUTHOR]

We performed a comparative study of the total bacterial communities and communities of cultivable polycyclic aromatic hydrocarbons (PAH)-degrading bacteria in different functional zones of Moscow and Murmansk that were formed under the influence of the PAH composition in road and leaf dust. The PAHs were determined by high-performance liquid chromatography (HPLC); the bacterial communities' diversity was assessed by metabarcoding. The degraders were isolated by their direct plating on a medium with the PAHs. The PAH total quantity declined in the leaf dust from the traffic to the recreational zone. For the road dust, a negative gradient with pollution was observed for Rhodococcus and Acinetobacter degraders and for their relative abundance in the microbiome for the functional zones of Moscow. The opposite effect was observed in the Murmansk leaf dust for the Rothia and Pseudomonas degraders and in the Moscow road dust for Microbacterium. The PCA and linear regression analyses showed that the Micrococcus degraders in the dust were sensitive to anthropogenic pollution, so they can be used as a tool for monitoring anthropogenic changes in the biosphere. The data on the degraders' and microbial communities' diversity suggest that minor degrading strains can play a key role in PAH degradation. [ABSTRACT FROM AUTHOR]