Detection Of Microbial Aaerosol PM2.5,PM10 In Dairy Farm And Assessment Of Its Environmental Conditions

In view of the problems of intensive,large-scale dairy herds,difficult environmental sanitation and disease control,this study selected a representative large-scale dairy farm to detect the main components and contents of environmental microorganisms and evaluate its sanitary status.In this study,ZR-3920 ambient air particulate matter(TSP/PM10/PM2.5)sampler,international standard ANDERSEN-6 impact air microbial collector and AGI-30(All Glass Impinger AGI-30)all glass liquid impact air microbial collector were used to collect microbial aerosol from three different farms(lactation,calf and ward)in a dairy farm in Hefei suburb,Anhui Province.Airborne bacteria,airborne fungi,airborne endotoxin,PM2.5 and PM10 microbial components were detected to objectively evaluate the pollution of microbial aerosol to the environment of cowshed and the potential harm to the health of cows and breeders.The samples were collected by the international standard ANDERSENN-6 impact air microbial collector.Aerobic bacteria,Escherichia coli,Staphylococcus,Gram-negative bacteria and fungi were collected by 5%agar medium of ram blood,Eosin methylene blue medium,Staphylococcus selective agar,Gram-negative bacteria selective medium and Sabouraud medium respectively.Nine groups were collected in parallel in each dairy house.The test results showed that the total number of airborne aerobic bacteria:4.75×10~3-3.72×10~4CFU/m~3air,airborneE.coliconcentration:1.2×10~2-1.6×10~3CFU/m~3,airborne Staphylococcus aureus concentration:5.4×10~2-4.27×10~3 CFU/m~3,concentration of airborne Gram-negative bacteria:1.5×10~2-2.06×10~3CFU/m~3,airborne fungal concentration:5.8×10~2-2.76×10~3CFU/m~3.The aerodynamic diameter analysis of the sample showed that the particle size of the aerobic bacteria was greater than 4.7?m,accounting for 28.1%-35.6%,partially blocked by the nasal cavity,and some were able to enter the upper respiratory tract.55.0%-57.2%of the particles are in the range of 2.1-4.7?m and can enter the lower respiratory tract.They are mainly suspended in the air and settle slowly.The particle size of 7.8%-15.8%is between0.6 and 2.1?m,which belongs to PM2.5.It can enter the lower respiratory tract and alveoli,and the risk of pathogen infection is increased.E.coli:25.9%-29.9%of the particle size?4.7?m,54.3%-63.2%of the particle size is between 2.1 and 4.7?m,10.9%-15.8%of the particle size is between 0.6 and 2.1?m.Staphylococcus:24.6%-29.3%of the particle size?4.7?m,50.2%-57.9%of the particle size is between 2.1 and 4.7?m,and 14.6%-22.4%of the particle size is between 0.6 and 2.1?m.Gram-negative bacteria:29.1%-32.0%of particle size?4.7?m,49.6%-61.6%of particle size between 2.1-4.7?m,8.1%-18.4%of particle size between 0.6-2.1?m.Fungi:25.4%-37.1%of particle size?4.7?m,49.9%-62.7%of particle size between 2.1-4.7?m,10.8%-14.7%particle size between 0.6-2.1?m.The bacterial identification results of ANDERSEN-6 level sampler 5 and 6 showed that Staphylococcus and Bacillus were the dominant bacterial groups,among which Staphylococcusgallinarum,Staphylococcussaprophyticus,Staphylococcusxylosus,Staphylococcus caprae,Staphylococcus haemolyticus,Staphylococcus chromogenes were the conditional pathogenic bacteria.All Glass Impinger AGI-30(all Glass Impinger AGI-30)all glass liquid impact air microbial collector was used to collect airborne endotoxin.The concentration of endotoxin was between14.73 EU/m~3 and 70.71 EU/m~3,which did not exceed the recommended value for occupational contacts of 90 EU/m~3.Bacteria and fungi in PM2.5 and PM10 samples collected by ZR-3920 ambient air particulate matter(TSP/PM10/PM2.5)sampler were detected by 16S rRNA and ITS high-throughput sequencing techniques.The dominant bacteria of PM2.5 and PM10 samples at genus level:Corynebacterium,Jeotgalicoccus,Streptococcus,Lactobacillus,Micrococcus,Brevibacterium,Facklamia,Brachybacterium,Acinetobacter,Psychrobacter.The dominant fungi of PM2.5and PM10 samples at genus level:Cladosporium,Aspergillus,Sporidiobolus,Alternaria,Phaeosphaeria,Bullera,Gibberell,Epicoccum,Trametes,Pleurotus.The species richness and distribution uniformity of PM2.5 and PM10 bacterial samples in cowshed were slightly higher than those of fungal samples.The diversity of PM2.5 bacterial samples from cow wards and PM2.5 fungi samples from lactating cow houses were significantly different from that of other cow houses.The species richness and distribution uniformity of the bacterial samples of PM2.5 and PM10in each barn were slightly higher than those of the fungal samples.The diversity of PM2.5bacterial samples from cow wards and PM2.5 fungi samples from lactating cow houses were significantly different from that of others.PM2.5 concentration ranged from 115 to 152?g/m~3,PM10 concentration ranged from 124 to189?g/m~3,exceeding the national environmental air quality standard limits of 75?g/m~3 and150?g/m~3.High concentration of fine particulate matter enters the bronchus,which goes directly to the alveoli and damages the respiratory system,which poses a threat to the health of dairy cows and feeders.