Bacterial Community Response To Major Environmental Pollution In PM_2.5during Heating Period In Taiyuan

Rapid industrialization and urbanization in China lead to widespread air pollution recent years,which posing great harm to human health.As the culprit,PM_2.5 has attracted more and more at the same time.In this study,we collected PM_2.5 during the heating season in Taiyuan,Shanxi.The contents of heavy metals,water-soluble ions and 16 PAHs attached to the particles were measured by inductively coupled plasma mass spectrometer?ICP-MS?,ion chromatography and gas chromatography-mass spectrometer?GC-MS?respectively,revealing PM_2.5 pollution characteristics during heating season.Subsequently,16 S r RNA sequencing was used to compare the difference of microbial community structure under hazy days and non-haze days in PM_2.5.Real-time quantitative PCR is used to accurately quantify the absolute abundance of antibiotic resistance genes?ARGs?and mobile genetic elements?MGEs?in particulate samples.The aim of this research is to clarify the interactions between microorganisms and major environmental pollution components and possible molecular mechanisms in particulate matter during heating period.The results showed:?1?PAHs with a few number of rings had stronger interaction with microorganisms because of low molecular weight and simple structure of PAHs.The concentration of PAHs increased significantly on hazy days,and the Proteobacteria and Fusobacterium considerably enriched at the level of phylum,Sphingomonas,Novosphingobium and Skermanella were dominated at genus in PM_2.5 on hazy days,suggesting these bacterial had a strong tolerance to PAHs.At the same time,we found that pathogenic bacteria related to respiratory system disease significantly enriched in PM_2.5 on haze days.Gram-negative bacteria?Gram-?were more tolerant to PAHs than Grampositive bacteria?Gram+?.Moreover,the hydroxylation of aromatic rings of the microbial communities were well-adapted to tolerate PAHs bound on PM_2.5 by functional analysis of the microbial community.?2?The PMF model results showed that there were four main sources of PM_2.5 during the heating period in Taiyuan: traffic,coal combustion,secondary aerosols and industry.Secondary aerosols had the greatest impact on microbial communities,followed by coal combustion,traffic and industry.Heavy metals and water-soluble ions had a significant correlations with microbial communities in PM_2.5.We also found that the contents of heavy metals V,Mn,Co,Ni and As had a strong correlation with the absolute abundance of resistance genes of Quinolones,macrolides and part tetracycline but had little correlation with water-soluble ions.Our results suggested that heavy metals and water-soluble ions can directly affect the host community of ARGs in PM_2.5.At the same time,ARGs were transferred horizontally by the MGEs,which accelerating the transfer and spread of ARGs between microorganisms and makes microbial community generally acquire antibiotic resistance.