Bacterial Communities in Marine Aerosols Revealed by 454 Pyrosequencing of the 16S rRNA Gene*

Abstract

Although bacteria are an important biological component of aerosol particles, studies of bacterial communities in remote marine aerosol are largely lacking. In this study, aerosol samples were collected over the western Pacific Ocean, the northern Pacific Ocean, the Arctic Ocean, and the Norwegian Sea during the Fifth Chinese National Arctic Research Expedition (CHINARE 5). The diversity and structure of aerosol bacterial communities, based on 454 pyrosequencing, were explored in these samples. The bacterial community in the aerosols collected over the Pacific Ocean was more diverse than over the Norwegian Sea. Both temporal and spatial variations in aerosol bacterial communities were observed based on phylogenetic analysis. These results suggest that the source of air masses shape bacterial communities in aerosol particles over remote marine regions. Aerosols are clearly important for long-range transport of bacteria. Since potential human pathogens (e.g., Streptococcus sp.) were retrieved in this study, further investigation is needed to evaluate the potential for their long-distance migration via aerosol.

Aerosol Microbiome over the Mediterranean Sea Diversity and Abundance

“…The average number of OTUs in our aerosol samples collected during springtime was similar to the number of OTUs in the Norwegian Sea and the Western Pacific in the summer and lower than OTUs in the Northern and Western Pacific Ocean in the fall [56]. Since seasonality impacts airborne bacterial abundance [12,19] and community composition [56], spatiotemporal variability of airborne microbes should be studied during other seasons to assess interannual variability in this region. The number of observed OTUs during non-storm conditions was lower than those measured in coastal cities in the Mediterranean during dust storms [31,58].…”

“…'Common' organisms found over the Mediterranean Sea in this study compared to five studies focusing on marine aerosols [1,8,38,55,56], five studies focusing on coastal aerosols [3,31,32,57,58], and six samples from one study focusing on Mediterranean surface seawater [59]. Columns under open ocean studies refer to references [1,8,38,55,56], columns under Mediterranean coastal studies refer to references [3,31,32,57,58], and columns under Mediterranean seawater samples refer to six samples from reference [59]. To quantitatively assess the diversity and estimate the differences in airborne bacterial communities over the MS, we report microbial community richness, expressed as the number of unique OTUs observed, and diversity expressed as Shannon's diversity index (H), estimated from the abundance of bacteria in each sample (Table 1).…”

“…When compared to airborne bacteria in samples collected on the Mediterranean coast [3,31,32,57,58] (Tables 2 and 3), 48% of the common bacteria and 13% of the rare bacteria found in our study were also reported in these studies at the family level. Highly abundant families (Bacillaceae, Sphingomonadaceae, and Pseudomonadaceae) were also found in the air over other marine environments [1,8,56] at the class level, suggesting that these organisms are commonly dispersed via airmasses. If these organisms are viable upon deposition and have a cosmopolitan distribution throughout the oceans, it could be inferred that airmasses are a vehicle of biogeographical distribution.…”

“…There are only a few studies which have identified and reported airborne microbial diversity in open ocean settings. However, the few reports cover diverse ocean basins, including the East China Sea [54], Caribbean Sea [8], Norwegian Sea [56], Atlantic Ocean [1,8], Pacific Ocean [1,56], and the Indian Ocean [1]. All these studies identified organisms at the family level, except for Mayol et al [1], which identified organisms at the class level.…”

Improved identification of primary biological aerosol particles using single particle mass spectrometry

“…Bioaerosol tend to be primarily bacteria and some fungal spores, although pollen (O'Connor et al, 2014) and possibly viruses (Griffin et al, 2001) have been reported. Some studies have performed DNA analysis of bioaerosol, reporting a wide diversity (Smith et al, 2012Xia et al, 2015).…”