| Concentration of airborne endotoxin, bioaerosol including its concentration and composition were measured in two different fox farms. At the same time, the quantitative relationship between the concentrations of airborne endotoxin and airborne gram-negative bacteria was analyzed. The composition of the airborne aerobic gram-negative bacteria cluster was identified. We can deduce the dangerous to animal and human's health in terms of the distribution of airborne microbiological aerosol particle in Anderson six-stage sampler. And we analyzed the concentration of endotoxin and gram-negative bacteria in feedingstuff and feces deduced that the main source of airborne endotoxin and airborne gram-negative bacteria. Finally, analyzing airborne endotoxin and bioaerosol in defferent seasons. Through this experiment, we laid the foundation to study and form a appropriate farming model of fox feeding to settle the conflict between economic benefits and environment benefits.The study consists of three parts:Part I: The concentrations of airborne endotoxin and bioaerosolThe concentrations of airborne aerobic bacteria and airborne gram-negative bacteria were measured by using Andersen-6 sampler for samping and 5% buck blood-blood agar foundation media served as medium. Moreover, the concentration of the airborne gram-negative bacteria and airborne aerobic bacteria were identified with gram-staining and API-array. Airborne endotoxin concentrations were determined using AGI-30 impinger and the Limulus amebocyte lysate (LAL) assay. Air samplers were collected in 50 ml BET water. The results indicated that the number of total airborne aerobic bacteria varied from 4.52×10~2 to 2.87×10~4CFU/m~3, the number of airborne anaerobic bacteria varied from 3.50×102 to 1.72×104 CFU/m3,the number of airborne facultative anaerobic bacteria varied from 3.20×102 CFU/m3 to 1.53×104CFU/m3,the number of airborne aerobic gram-negative bacteria from 4.07×101 to 4.43×103CFU/m3, The total amount airborne endotoxin 2.41×101 to 2.09×103 EU/m3.Moreover, the quantitative relationship between the concentrations of airborne endotoxin and airborne gram-negative bacteria were analyzed. Inapparent correlation were found in this two rabbitries between the concentration of airborne endotoxin and airborne gram-negative bacteria (r1=0.54,r2=-0.262).So the total number of the airborne gram-negative bacteria should not be used for the estimation of the concentration of airborne endotoxin.PartⅡ: The concentration and composition of airborne gram-negative bacteria and its aerodynamic diameter (Dae50)In this experiment, we measured the concentration and composion of airborne gram-negative bacteria. At first, the gram-negative bacteria was identified by using the gram-staining; Second, airborne gram-negative bacteria was divided into Enterobacteriaceae and no- ferment bacteria by O-F-array and oxidation enzyme-array, which were identified by API-20E and API-20NE respectively. The results indicated that about 8.43%~16.61% of the total number airborne aerobic bacteria were identified as airborne gram-negative bacteria. The main airborne aerobic gram-negative bacteria family included the Enterobacteriaceae, the Pasteurella and the Pseudomonas Within the family of the airborne aerobic gram-negative bacteria the species Enterobacteriaceae was predominant and we have not detected the obligate anaerobic airborne gram-negative bacteria in this experiment. The species Enterobacteriaceae is about 83.2%~89.4% of the total bacteria, the Pasteurella and the Pseudomonas is 5.2%~10.7% and 5.4%~6.1% of the total bacteria.In addition, the distribution of airborne gram-negative bacteria on the single stage of the Andersen sampler were analyzed, it concluded that about 24.6% airborne gram-negative bacteria distributed at A stage with aerodynamic diameters ranged from 8.5μm to 20μm and 36.9% distributed at c stage with aerodynamic diameters ranged from 2μm to 6μm which can reach trachea and bronchia even bronchiole, make severe threatening for stockmen and animals'respiratory tract.PartⅢ:The analysis on the resources of airborne endotoxin and airborne aerobic gram-negative bacteria in two fox farmsThe concentration of airborne endotoxin, airborne gram-negative bacteria airborne facultative anaerobic bacteria and airborne aerobic bacteria were detected in the air outside the two fox farms. The concentration of endotoxin, gram-negative bacteria, facultative anaerobic bacteria and aerobic bacteria were detected in feedingstuff and feces too. Then, we analyzed the quantitive relationship between the airborne endotoxin, the airborne aerobic gram- negative bacteria the airborne facultative anaerobic bacteria and that in feedingstuff or feces. The concentration of airborne endotoxin,airborne gram-negative bacteria,airborne facultative anaerobic bacteria and airborne aerobic bacteria were 1.1EU/m3~3.00×102EU/m3,1.6×101~1.02×103CFU/m3 1.03×102~8.64×103 CFU/m3 and 1.74×102~1.11×104CFU/m3 respectively in the air at the distance of 5m outside of the two fox farms. We have not detected the obligate anaerobic airborne gram-negative bacteria in this experiment. The concentration of endotoxin reached 5.43×103~4.23×104EU /g,6.96×103~5.64×104EU/g,gram-negative bacteria reached 4.80×103~ 3.81×105CFU/g,1.38×104~7.80×105CFU/g, aerobic bacteria reached 4.69×104 ~2.65×105CFU/g,3.33×104~2.59×106CFU/g, facultative anaerobic bacteria reached 3.90×103~1.78×105CFU/g,1.50×104~6.77×105 CFU/g respectively in feedingstuff and feces in two fox farms. So we can see from the results that feedingstuff and feces are the main source of airborne endotoxin and airborne gram-negative bacteria in two fox farms.The correlation and regression analysis on the concentration of the airborne endotoxin and the airborne aerobic gram-negative bacteria that in the feces and the feed were carried out. Analysis indicated the airborne endotoxin in the fox farm were positive relative with the concentration of the endotoxin in feces and the feed(0.010.05). These results indicated the feces and the feed were the most important resources for the airborne endotoxin and airborne aerobic gram-negative bacteria in two fox farms, but other resources maybe exist.PartⅣ:The analysis on the change of airborne endotoxin and bioaerosol in two fox farms in different seasons.The study measured the concentration of airborne endotoxin and bioaerosol in different seasons and analyzed the change between them. The results indicated that in summer the number of total airborne aerobic bacteria varied from 5.63×102 to 2.87×104CFU/m3, the number of airborne facultative anaerobic bacteria varied from 1.04×103 to 1.67×104CFU/m3,the number of airborne aerobic gram-negative bacteria from 4.07×101 to 3.47×103CFU/m3, The total amount airborne endotoxin 2.67×101 to 2.05×103EU/m3; in autumn the number of airborne aerobic bacteria varied from 4.52×102 to 2.31×104 CFU/m3, the number of airborne facultative anaerobic bacteria varied from 6.78×102 to 1.72×104CFU/m3,the number of airborne aerobic gram-negative bacteria from4.07×10 to 4.22×103CFU/m3, the total amount airborne endotoxin 2.70×101 to 2.09×103EU/m3;in winter the number of airborne aerobic bacteria varied from 4.52×102 to 2.58×104CFU/m3, the number of airborne facultative anaerobic bacteria varied from 3.53×102 to 1.46×104CFU/m3,the number of airborne aerobic gram-negative bacteria from4.58×101 to 4.43×103CFU/m3, the total amount airborne endotoxin 2.40×101 to 1.84×103EU/m3.The most number of airborne aerobic bacteria,airborne facultative anaerobic bacteria and airborne aerobic gram-negative bacteria existed in summer and autumn,and airborne endotoxin varied not significantly. The results showed the number of bioaerosol changed with seasons significantly, we should paid more attention to the disinfection and preventing in summer and autumn.
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