Genomic and Phenotypic Classification of Staphylococcus Species Isolated From Delhi Air.

To understand the prevalence of opportunistic bacterial pathogens in the bioaerosols, outdoor air-sampling was performed during the peak season of air pollution prior to the onslaught of the COVID-19 pandemic in the national capital of India, Delhi, during the month of November 2019. Employing a sophisticated plate exposure technique using the Merck Mas Eco-100 instrument, culturable bacterial samples were collected from six locations in Delhi. Among the identified bacterial samples, multiple species of the opportunistic pathogen Staphylococcus, namely, S. gallinarum, S. haemolyticus, and S. arlettae were present. To further characterize these isolates, whole genome sequencing coupled with phenotypic microarray, antibiotic resistance profiling, and biofilm formation in the presence of a known air pollutant, black carbon, was performed. The comparative genomics analysis highlighted the presence of the urease gene cluster (ureABCDEFG) in S. arlettae Naraina and S. haemolyticus Yojna Vihar 1 that may provide a fitness advantage to these strains, as urease activity in S. haemolyticus and S. arlettae is usually reported as negative.