Airborne bacterial community diversity, source and function along the Antarctic Coast.

Antarctica is an isolated and relatively simple ecosystem dominated by microorganisms, providing a rare opportunity to study the spread of airborne microbes and to predict future global climate change. However, little is known about on the diversity and potential sources of microorganisms in the marine atmosphere along the Antarctica coast. Here we explored the airborne bacterial community (i.e., bacteriome) diversity, sources and functional potential along the Antarctic coast based on 16S rRNA gene amplicon sequencing of 25 bioaerosol samples collected during the 33rd Xuelong Antarctic scientific expedition. The results showed that bacterial communities in the Antarctic bioaerosols i) were predominated by Proteobacteria (91.3%) including Sphingomonas, ii) showed relative low alpha-diversity but high spatiotemporal variabilities; and iii) were potentially immigrated with terrestrial, marine and Antarctic polar bacteria through long-range transport and sea-air exchange pathways. Moreover, canonical correspondence analysis of bacteriome composition showed that wind speed, temperature, and organic carbon had a significant effect on the bacterial community (P < 0.05), although bacterial richness (Richness index) and diversity (Simpson index and Shannon index) showed no statistically significant differences between rainy, cloudy and snowy weather conditions (Adjust P > 0.05, ANOVA, Tukey HSD test). iv) The functional profiles predicted by Tax4fun2 suggest high representation of function genes related to fatty acid biosynthesis and metabolism, amino acid metabolism, nucleotide metabolism, and carbohydrate metabolism, which is conducive to the formation of microlayers on the surface of the ocean and the survival and growth of bacteria.