江苏泰州城市霾天和沙尘天气溶胶中细菌群落结构特征研究

Airborne Bacterial Community Characteristics During Dust and Haze Days in Taizhou City of Jiangsu Province

近年来,空气污染已成为长三角地区最关键的环境问题之一,气溶胶颗粒物(PM)是最主要的污染物之一。生物气溶胶作为颗粒物的重要组成部分,可能对空气质量和人体健康产生不利影响。利用高通量测序方法研究了江苏省泰州2019年11月至2020年1月期间发生沙尘和霾污染时生物气溶胶中细菌群落结构组成特征。结果表明:冬季沙尘天和霾天气溶胶细菌群落结构及多样性呈现不同的变化特征,霾天细菌群落多样性、均匀度以及基于进化的多样性明显高于夏季优良天,粒径差异增大;沙尘天细菌群落结构变化和霾天正好相反,不仅大气微生物丰富度会降低,细菌群落结构的多样性和均匀度也会降低。优良天粗细颗粒的细菌群落组成和优势种相似度较高,沙尘和霾污染天粗细颗粒间的细菌组成差异较大,病原细菌的种类和相对丰度也明显增加,优势类群中致病菌浓度上升的主要有假单胞菌属(Pseudomonas)、雷氏菌属(Ralstonia)、肠球菌属(Enterococcus)、拟杆菌属(Bacteroides)、埃希氏菌-志贺氏菌属(Escherichia-Shigella)、链球菌属(Streptococcus)等,增加了人类、动物及农业生产活动潜在的暴露风险。基于丰度热图分析污染天各粒径的细菌群落结构相似性,沙尘天大部分粒径聚在一起,粒径间的细菌组成相似性较高;霾天样品的粒径分布总体较分散,随着污染加重,粒径差异有增大的趋势。

In recent years,air pollution has become one of the most critical environmental issues in the Yangtze River Delta region,with particular matter(PM)being one of the top pollutants.As an important fraction of PM,bioaerosols may have adverse effects on air quality and human health.Airborne bacterial community characteristics during dust and haze days from Nov.2019 to Jan.2020 in Taizhou City were studied using Illumina high-throughput sequencing.The results showed that the bacterial community structure and diversity in bioaerosols varied significantly when the dust and haze occurred in winter.In haze days,the diversity,evenness and evolution-based diversity of airborne bacteria were significantly higher than good days in summer,the difference among particle sizes was also increased.In dust days,change in bacterial community structure was just the opposite of haze days,not only the abundance of airborne microorganisms decreased,but also the diversity and evenness decreased.In good days,the bacterial community composition and dominant species between coarse particles and fine particles were relatively similar.During dust and haze event,the differences of bacterial composition between coarse particles and fine particles increased,the species and relative abundance of pathogenic bacteria were also obviously increased,the increased concentration of pathogenic bacteria in dominant groups were Pseudomonas,Ralstonia,Enterococcus,Bacteroides,Escherichia-Shigella,Streptococcus,which may bring potential health risks to human,animal and agricultural production activities.Based on abundance heatmap analysis of the bacterial community structure similarity of different particle sizes in polluted days,most of the particle sizes were clustered together in dust days,which indicated that the high similarity in the bacterial composition among particle sizes.In general,the particle sizes samples of the haze days were scattered,and the particle size difference increased with the increased pollution.