Investigation of diverse bacteria in cloud water at Mt. Tai, China

- Bacterial community in cloud water of Asian area was studied for the first time.
- High throughput sequencing revealed diverse gram-negative bacteria mainly inhabiting in leaf-surface and cold environments.
- Bacteria involved in the cloud condensation nuclei and ice nucleation process were observed.
- SO2 and O3 distinctly contributed to the variations of species-environment relationship in different samples.

Bacteria are abundant in atmospheric water phase with the potential to influence atmospheric processes and human health, yet relatively little information is known about the bacterial characteristics at high altitudes. Here we investigated the bacterial community by high throughput sequencing in 24 cloud water samples collected from September 26 to October 31, at the summit of Mt. Tai (36°15′ N, 117°06′ E, 1534 m a.s.l) in China. Diverse bacterial population were identified and the gram-negative bacteria contributed the majority of total bacteria including Proteobacteria (81.6%) and Bacteroidetes (3.9%), followed by gram-positive bacteria Firmicutes (7.1%) and Actinobacteria (2.3%). These gram-negative taxa mainly inhabited in leaf-surface and cold environments. Meanwhile bacteria involved in the cloud condensation nuclei and ice nuclei formation were observed such as Sphingomonas (6.7%), Pseudomonas (4.1%), and Bacillus (1.1%). In addition, Sphingmonas was more active than that in daytime and participated in the cloud chemistry process. Meanwhile O3 and SO2 critically contributed to the variation of bacterial community. It is the first report on the bacterial community structure of cloud water over Asian area. Our results can serve as an important reference for environmental scientists, and biologists.

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