In order to study E. coli aerosol spreading from chicken houses to their surrounding air, air samples, including indoor and outdoor air (upwind 10 and 50 m as well as downwind 10, 50, 100, 200 and 400 m away) of 5 chicken houses were collected using six-stage Andersen microbial samplers and Reuter-Centrifugal samplers (RCS). E. coli concentrations (CFU/m3 air) collected from different sampling sites were calculated. E. coli strains from chicken feces samples were also isolated. Furthermore, the enterobacterial repetitive intergenic consensus (ERIC)-PCR method was applied to amplify the isolated E. coli strain DNA samples. Through the genetic similarity analyses of the E. coli obtained from different sampling sites, the spreading of bioaerosol from animal houses to the ambient air was characterized. The results showed that the isolated E. coli concentrations in indoor air (9―63 CFU/m3) in 5 chicken houses were higher than those in upwind and downwind air, but there were no significant differences between the indoor and downwind sites 10 m away from all the 5 houses (P>0.05). The phylogenetic tree indicated that a part of the E. coli (34.1%) isolated from indoor air had 100% similarity with those isolated from feces, and that most of E. coli isolated (54.5%) from downwind at 10, 50, 100 or even 200 m had 100% similarity with those isolated from indoor air or feces too. But those isolated from upwind air had a lower similarity (73%―92%) with corresponding strains isolated from indoor air or feces. Our results suggested that some strains isolated from downwind air and indoor air originated in the chicken feces, but most of isolates obtained from upwind air samples did not come from the chicken feces or indoor air. Effective hygienic measures should be taken in animal farms to prevent or minimize downwind spreading of microorganism aerosol.
兔舍内气载内毒素的含量介于65￣217 EU/m 3;需氧革兰氏阴性活菌的含量介于0.7￣1.6×103 C FU/m 3空气之间,占优势的是肠杆菌,其中大肠杆菌最为常见;需氧菌含量介于3.3￣7.8×103 C FU/m 3。气载内毒素与需氧革兰氏阴性活菌含量和需氧菌总数在数值上存在弱的正相关(r=0.23;r=0.20)。结果表明:不能通过测定气载革兰氏阴性细菌或细菌总数来估计气载内毒素的含量。气载内毒素含量与粪便和饲料中内毒素浓度之间呈正相关(r=0.71;r=0.58),证明饲料和粪便是气载内毒素的重要来源。
