[Concentration and Particle Size Distribution Characteristics of Microbial Aerosol and Bacterial Community Structure During Spring in Lanzhou City, China]

The aim of this study was to analyze the differences in the concentration, particle size, and bacterial community structure of microbial aerosols and further investigated the effects of meteorological conditions and air pollutants on microbial aerosol distribution at different periods during spring in Lanzhou. The results showed that the average aerosol concentrations of total microbes, bacteria, fungi, and actinomycetes in the air environment of Lanzhou were (2730±376), (2243±354), (349±38), and (138±22) CFU·m^-3, respectively. The contribution rate of bacteria was 82.16%, which was significantly higher than that of fungi and actinomycetes (P<0.05). The concentrations of total microorganisms, bacteria, and actinomycetes during 08:00-09:00 were significantly higher than those sampled during 18:00-19:00, indicating that meteorological conditions and air pollutants have a remarkable influence on the concentration of microbial aerosols. Aerosol particles of bacteria and fungi were primarily distributed at the first four levels (>2.1 μm), accounting for 85.13% and 83.26%, respectively, while 73.15% of the actinomycetes aerosol particles focused largely on the latter four stages (<4.7 μm). Illumina MiSeq sequencing results indicated that there was no significant difference in the composition of the bacterial community (P>0.05) during the periods of 08:00-09:00 and 18:00-19:00. Lactococcus and Bacillus were the dominant bacteria genus. Enterococcus, Staphylococcus, Pseudomonas, Acinetobacter, Klebsiella, Erwinia, Bacillus cereus, Streptococcus agalactiae, and Clostridium perfringens were potential pathogens detected in the air environment of Lanzhou in the spring. The results could provide fundamental data for further revealing the contamination status of microbial aerosols and the potential harm of the related pathogenic bacteria to human health during the spring in Lanzhou.