[Community Characteristics of Cultivable Bacteria in Fine Particles(PM) of Beijing and Baoding].

Fine particles(PM) collected by two middle volume air samplers in the suburbs of Baoding and the urban area of Beijing during Jan 10 to 17, 2015, were used to compare the community characteristics of cultivable bacteria in the two sites. In this study, we observed the particle morphology of PM using a field emission scanning electron microscope (FESEM), analyzed the air mass transportation source of the two sampling sites by the NOAA/ARL HYSPLIT-4 backward trajectory model, and measured the concentrations of the major water-soluble ions and heavy metal elements in the PM samples using ion chromatography, continuous flow analyzer and ICP-MS. The results indicated that, the cultivable bacteria of PM contained three phyla, which were Firmicutes, Actinobacteria and -Proteobacteria. Nine genera and 17 species of cultivable airborne bacteria were isolated and identified. The most abundant phylum was Firmicutes. The Gram-positive bacteria accounted for more than 90%. The spore-forming which was the dominant species contributed 68.15% and 75% to the total bacteria in urban Beijing and the suburbs of Baoding, respectively. The difference in the community structure of PM's cultivable bacteria in the two sampling areas may be affected by PM's physical and chemical properties and air mass transportation.