Assessment of bioaerosols at a concentrated dairy operation |
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Authors: | Robert S Dungan April B Leytem Sheryl A Verwey David L Bjorneberg |
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Institution: | (1) Northwest Irrigation and Soils Research Laboratory, Agricultural Research Service, US Department of Agriculture, 3793 North 3600 East, Kimberly, ID 83341, USA |
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Abstract: | Increased bioaerosol loadings in downwind plumes from concentrated animal feeding operations (CAFOs) may increase the risk
for allergy and infection in humans. In this study, we monitored airborne concentrations of culturable bacteria and fungi
at upwind (background) and downwind sites at a 10,000 milking cow dairy over the course of a year. The average bacterial concentrations
at the upwind site were 8.4 × 103 colony forming units (CFU) m−3 and increased to 9.9 × 105 CFU m−3 at the downwind edge of the cattle lots, decreasing to 6.3 × 104 CFU m−3 200 m farther downwind. At the same sites, the average fungal concentrations were 515, 945, and 1,010 CFU m−3, respectively. Significant correlations between the ambient weather conditions and airborne fungal and bacterial concentrations
were identified. Sequence analysis of PCR-amplified DNA from bacterial clones and fungal isolates revealed genus and species
level differences between upwind and downwind sites. Although we could not cultivate gram-negative bacteria, bacterial clones
at downwind sites identified as being gram-negative matched with the following genera: Acinetobacter, Bradyrhizobium, Escherichia, Idiomarina, Methylobacterium, Ralstonia, and Novosphingobium. Fungal isolates from downwind matched with the following genera: Acremonium, Alternaria, Ascomycte, Aspergillus, Basidiomycete, Cladosporium, Davidiella, Doratomyces, Emericella, Lewia, Onygenales, Penicillium, Rhizopus, and Ulocladium. None of the bacterial and fungal sequence matches were affiliated with genera and species known to be pathogenic to humans.
Overall, the data suggest that exposure to bioaerosols in the downwind environment decreases with increasing distance from
the open-lot dairy. |
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