Study On The Distribution Characteristics Of Microorganisms In PM_2.5 In Winter In Xi'an And Linfen

Accumulating evidence suggests that particulate matter in ambient air could carry pathogenic microorganisms which might had adverse effects on human health.Microorganisms of fine particulate matters can cause skin allergies and respiratory diseases.However,most of the recent studies have only focused on its physicochemical properties,and studies about its microbial compositions were rare.Besides,many researches focus on heavy polluted cities but ignore the typical cities which were small and medium-sized,and the comparations of the typical cities were less.This study collected PM_2.5 samples from Xi'an and Linfen in winter,and then analyzed and compared microbes by 16S rRNA and18S rRNA gene high-throughput sequencing.Alpha analysis was used to reflect the abundance and diversity of microbes in the samples.The PICRUSt method was used to predict and analyze the function of genes and RDA analysis was used to investigate the correlation between environmental factors and microorganisms.This study discussed the distribution of microbes focusing on different regions,different conditions.This paper was used to provide a reference for further understanding of the distribution characteristics of microorganisms in particulate matter.The main contains and results are as follows:?1?By analyzing the distribution characteristics of microorganisms of PM_2.5 in different regions in winter,we found that the abundance of bacteria was significantly higher than that of Linfen?p<0.05?,and the diversity was lower than that of Linfen.Similarly,the abundance and diversity of fungi in Xi'an were higher than those in Linfen.At phyla,bacteria were dominated by Proteobacteria and Actinomycetes.At order,bacteria were dominated by Rhizobiale and Oceanospirillales.While at genus,bacteria were dominated by Halomonas and Pelagibacterium.Similarly,at phyla,fungi were dominanted by Ascomycota,Phragmoplastophyta and Basidiomycota.At order,fungi were dominanted by Magnoliophyta,Hypocreales,Eurotiales and Malasseziales.At genus,they were dominanted by Aspergillus.The relative abundance of most pathogenic microbes and functional microorganisms in Xi'an were higher than those in Linfen.?2?By analyzing the distribution characteristics of microorganisms of PM_2.5 in Xi'an and Linfen under different conditions,we found that the dominant genus?Halomonas and Pelagibacterium?were more abundant in the conditions of light haze days and low concerntrations of SO₂ and NO₂ while the dominant genus?Aspergillus?were less abundant in the conditions of precipitation and low concerntrations of SO₂ and NO₂.The relative abundance of the dominant fungus was generally reduced during precipitation days.?3?The relative abundance of Rhodococcus,Halorubrum and Bacteroides in Linfen were higher than that in Xi'an,and the relative abundance of Rhodococcus and Halorubrum were higher in the conditions of non-haze,precipitation and low concerntrations of SO₂and NO₂.Bacteroides has an opposite trends which was less abundant in these conditions which were mentioned above.We also found the relative abundance of Rhodococcus in Linfen was 27.5 times than that in Xi'an might attribute to Linfen has the high concerntrations of SO₂.