A new study has shown that drift from a poultry farm moved aerosols onto a nearby almond orchard and altered the leaf microbiome. The study was published in Applied and Environmental Microbiology. Raw almonds have been linked to Salmonella outbreaks in the past. There were also outbreaks linked to raw almonds in 2000 and 2005 in California, and in 2012 in Australia.
The movement of pathogens from animal operations into adjacent plant crop fields is not well characterized. The study showed that dust and bioaerosols moved from a commercial poultry operation a short distance into an almond orchard. The scientists found that the microbiome on the leaves was altered.
The study was conducted over a two year period. Swabs of orchard soil surface and air, soil, and almond leaf samples were collected in one orchard that was 35 meters away from a poultry operation, as well as two almond orchards, the controls, that were surrounded by other orchards. Samples were evaluated for aerobic plate count, generic E. coli, other coliform, and Salmonella.
The researchers looked at bacterial community structure through sequencing of the 16S rRNA gene, and the amounts of dust of leaf surfaces from specific trees in each orchard. E. coli was isolated from 41 to 206 and 2 of 207 air samples in the almond-poultry and control orchards, respectively. Salmonella was not isolated from any of the 529 samples evaluated. Drift from a poultry farm moved aerosols to the orchard.
On average, the mount of dry solids on leads collected from trees that were closest to the poultry operation was more than 2-fold greater than from trees 120 meters into the orchard or any trees in the control orchards. Members of the bacterial family Staphylococcaceae, which are often associated with poultry, were significantly more abundant in the phyllosphere of trees closest to the poultry operation. So in conclusion, “poultry-associated microorganisms from a commercial operator transferred a short distance into and adjacent downwind almond orchard,” according to the study.
