Spatio-temporal variations in bacterial and fungal community associated with dust aerosol in Kuwait

Kuwait is a country with a very high dust loading; in fact it bears the world's highest particulate matter concentration in the outdoor air. The airborne dust often has associated biological materials, including pathogenic microbes that pose a serious risk to the urban ecosystem and public health. This study has established the baseline taxonomic characterization of microbes associated with dust transported into Kuwait from different trajectories. A high volume air sampler with six-stage cascade impactor was deployed for sample collection at a remote as well as an urban site. Samples from three different seasons (autumn, spring and summer) were subjected to targeted amplicon sequencing. A set of ~ 50 and 60 bacterial and fungal genera, respectively, established the core air microbiome. The predominant bacterial genera (relative abundance ≥ 1%) were Brevundimonas (12.5%), Sphingobium (3.3%), Sphingopyxis (2.7%), Pseudomonas (2.5%), Sphingomonas (2.4%), Massilia (2.3%), Acidovorax (2.0%), Allorhizobium (1.8%), Halomonas (1.3%), and Mesorhizobium (1.1%), and the fungal taxa were Cryptococcus (12%) followed by Alternaria (9%), Aspergillus (7%), Candida (3%), Cladosporium (2.9%), Schizophyllum (1.6%), Fusarium (1.4%), Gleotinia (1.3%) and Penicillium (1.15%). Significant spatio-temporal variations were recorded in terms of relative abundances, α-diversities, and β-diversities of bacterial communities. The dissimilarities were less pronounced and instead the communities were fairly homogenous. Linear discrimant analysis revealed three fungal genera known to be significantly differentially abundant with respect to different size fractions of dust. Our results shed light on the spatio-temporal distribution of airborne microbes and their implications in general health.