Summary
Given the growing concerns over human and animal health issues related to confined animal feeding operations, an in‐depth examination is required to monitor for airborne bacteria and associated antibiotic resistance genes. Our 16S rRNA‐based pyrosequencing revealed that the airborne microbial community skewed towards a higher abundance of Firmicutes (> 59.2%) and Bacteroidetes (4.2–31.4%) within the confinement buildings, while the office environment was predominated by Proteobacteria (55.2%). Furthermore, bioaerosols in the confinement buildings were sporadically associated with genera of potential pathogens, and these genera were more frequently observed in the bioaerosols of pig and layer hen confinement than the turkey confinement buildings and office environment. High abundances of tetracycline resistance genes (9.55 × 102 to 1.69 × 106 copies ng−1 DNA) were also detected in the bioaerosols sampled from confinement buildings. Bacterial lineages present in the poultry bioaerosols clustered apart from those present in the pig bioaerosols and among the different phases of pig production, suggesting that different livestock as well as production phase were associated with a distinct airborne microbial community. By understanding the diversity of biotic contaminants associated with the different confinement buildings, this study facilitates the implementation of better management strategies to minimize potential health impacts on both livestock and humans working in this environment.
Ambient bioaerosols in PM 10 samples were measured at three sites in Corcoran, an agricultural town in the southern San Joaquin Valley (SJV) of California, during fall of 2000 corresponding to the cotton harvest season. Elevated bioaerosol concentrations were measured near grain elevators (GRA site) and a cotton handling facility (BAI site) as compared to levels in a residential community (COP site), ~2 km northeast of these sources. Average endotoxin levels (13 ± 17 EU/m 3 ) at the grain elevator site were three to eight times higher than averages at the nearby cotton-handling and residential sites. The highest level (47.6 EU/m 3 ) at the grain elevator site was about half of the exposure limit of 90 EU/m 3 set by the Dutch Expert Committee on Occupational Safety. Particle counts of fungal spore (66,333 particles/m 3 ) and pollen grain (2,600 particles/m 3 ) concentrations were more than double those reported in the literature. Average fungal biomarker concentrations of 170 and 131 ng/m 3 for arabitol and mannitol, respectively, were 1-2 orders of magnitude higher than those from nonagricultural areas. The low correlation (r < 0.11) of three fungal markers (i.e., (1→3)-β-D-glucan, arabitol, and mannitol) with fungi counts is consistent with findings by others and indicates that these are insufficient as surrogates to represent fungal exposure. Agricultural activities contributed measureable amounts to PM 10 mass and organic carbon (OC), dominated by fungal spores (i.e., 5.4-5.8% PM 10 mass and 11.5-14.7% OC). The sum of fungal spores, pollen grains, and plant detritus accounted for an average of 11-15% PM 10 and 24-33% OC mass. Bioaerosols can be important contributors to PM 10 mass in farming communities similar to Corcoran, especially during intense agricultural activities.
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