Preliminary Study On Bacterial Community And Variation In PM2.5 From Guangzhou Higher Education Mega Center

Fine particulate matter(PM2.5)contains amounts of the bacteria.Due to its small particle size and high fluidity,PM2.5 threats to public health.Plentiful river systems and hot,humid climates in Guangzhou benefit bacterial growth.Therefore,the studies focus on bacteria in the air are important.However,there were few studies revealed bacterial communities in PM2.5.According to the previous studies,large differences of bacterial community structure in aerosols from different regions were discovered.The microbial community highly correlated with climate and showed strong regional characteristics.Thus,it is necessary to study the microbial community composition and structure in our living environment.This study aim at the national strategic needs about air pollution control.We collected the bacterial community in PM2.5 from Guangzhou Higher Education Mega Center and designed the experiment based on interdisciplinarity.The microbial community structure in PM2.5 and their influence factors,such as wind direction and rainy season,were investigated based on 16 S r DNA gene sequencing.In addition,the potential pathogens were explored.This study deepens our understanding of the microorganisms distribution in similar areas,explores microbial aerosol transmission pathways and provides data for further toxicological research.The main contents and conclusions are listed as following:1.The bacterial community structure in PM2.5 and its influence factors from different wind direction was investigated.Proteobacteria dominated the bacterial community in Guangzhou Higher Education Mega Center PM2.5.Other dominant bacteria belonged to Bacteroidetes,Actinobacteria,Cyanobacteria,and Acidobacteria and so on.The abundance of different dominant species from various wind directions were different based on the Linear Discriminant Analysis Effect Size.The abundances of Cyanobacteria and Alphaproteobacteria increased when the wind originates from the ocean.When the wind is coming from the land,The Cytophaga-Flavobacteria cluster associated with freshwater planktonic bacteria rised when the wind came from the land.The impact factors on PM2.5 bacterial community structure were explored by redundancy analysis(RDA)and Pearson correlation analysis.It was found that the wind direction was the dominant factor causing the change of bacterial community structure in PM2.5.Wind speed also had great impact on bacterial community structure in PM2.5.The effect of PM2.5 concentration on bacterial community structure was caused by wind direction(p <0.01).2.Exploring the differences in bacterial community structure and potential human pathogens in PM2.5 during the rainy season.The dominant bacterial phyla in Guangzhou Higher Education Mega Center PM2.5 changed to Proteobacteria,Acidobacteria,Actinobacteria,Bacteroidetes and Verrucomicrobia when it rained.Among them,proteobacteria was the most abundant bacteria.Compared with the rain-free group from the same wind direction(NR group),there was a big change in the bacterial community structure in PM2.5.The rainy group(R group)contained many local ecosystem-related microorganisms,such as Acidobacteria and Burkholderiales,while the relative abundance of marine-derived marker species such as Cyanobacteria and Alphaproteobacteria reduced.Total of seven potential human pathogens were identified from the samples.Among them,Pseudomonas aeruginosa,Escherichia coli and Mycobacterium ulcerans were abundant.PM2.5 contained more abundant potential human pathogens when it rained.