Variations of airborne bacterial community with seasons and environmental factors in Changsha, China

The haze phenomenon has gradually spread from the northern to the southern regions with the rapid development of China’s economy in the last 10 years. In this study, we investigated the variation of air bacterial communities with seasons and air environmental factors in Changsha. Changsha is the core and node city of Hunan province, the home of nonferrous metals in China, and the province with the most serious heavy metal pollution in the country. We discovered that the most prevalent genera during the four seasons were Acinetobacter, Limnobacter, Methylobacterium, and Bacillus. Temperature, air quality index (AQI), and humidity were the key factors resulting in the change of air bacterial composition with seasons. Changsha’s air bacterial compositions were different from other sampling sites in China. There were many dominant or highly abundant genera tolerating extreme environments, such as Limnobacter, Saccharibacteria, Pseudomonas, Acidovorax, Massilia, Sphingomonas, and Cupriavidus, which may be related to the unique geographical environment of Changsha. Although Changsha is more than 2000 km away from the Asian dust source, we infer that on light pollution days (low AQI), especially in spring, Asian dust is an important source of pollution transmitted through long distances at high altitudes, while on heavy pollution days (high AQI), localized regional dust is the main source of pollution in Changsha.