Study On The Temporal And Spatial Distribution Of Particulate Matter And Microbial Aerosols In Closed Fattening Pigsty

In this study,a closed fattening pigsty in Hebei was selected as the sampling site.From September 2018 to February 2019,a TSI laser particle counter and Andersen-6 microbial aerosol sampler were used to close the fattening pig house on the farm.Internal microbial aerosols were monitored and sampled in real time.Through the methods of plate counting,sample DNA extraction,16 S r DNA sequencing and other methods,the aerosol particle size and concentration distribution rules and types in different time and space were analyzed and elaborated in detail.Test 1: Use TSI laser particle counter and Andersen-6 microbial aerosol sampler to detect microbial aerosol in the house.The results showed that there was no significant change in the microbial aerosol content at different times on the same day in the enclosed fattening pig house(P> 0.05),and the highest microbial aerosol concentration in the winter house.There was no significant change in the vertical distribution of particulate matter content,bacterial concentration and fungal concentration in the closed fattening pig house(P> 0.05),and the vertical distribution of microbial aerosol concentration was very balanced.A variety of harmful gases and environmental particulate matter in the pig house increased simultaneously.Test 2: Use Andersen-6 microbial aerosol sampler to collect microbial samples in the air of the house.The results showed that bacterial colonies decreased from STAGE-I to STAGE-VI levels in sequence.The number of bacterial colonies collected and cultured at STAGE-I level(particle size range> 8.2?m)was up to about 25%.There is a high positive correlation between the effective interception particle size of the layer and the percentage of the bacterial colony in the corresponding layer(r?0.8).Bacteria that can enter the lungs(particle size range <4.7?m)account for 51% to 58%.There is no high correlation between the fungi in each month,and the proportion of bacteria that can enter the lungs(particle size range <4.7?m)accounts for 62% to 77%.Through 16 s DNA sequencing,according to OTU classification,a total of 4268 OTUs of microorganisms were detected in air samples,and 2227 OTUs of microorganisms in air,feed and fecal samples.Test 3: The experiment selected 30 g 6-week-old BALB / C female mice,and were randomly divided into 3 treatment groups according to the initial body weight,namely the control group,the physiological saline nasal drip group and the particulate nasal drip group.One mouse was repeated for each.The control group was not treated.The nasal drip group received 50 ?L of nasal sample solution daily,and the saline nasal drip group received nasal equivalent of saline.The weight of mice in the nasal drops group was significantly reduced,and there was obvious edema and inflammation in the lungs.The results of this study revealed the evolution of the concentration of particulate matter and microbial aerosols in enclosed fattening pig pens,mastering the background of environmental pathogens,and providing a theoretical basis and technical support for the efficient protection of the breeding environment and safe production.