pathogen – Livestock and Poultry Environmental Learning Community

Purpose

Land applying agricultural and municipal wastes carries an inherent risk associated with nutrient and pathogen runoff and contamination, but with that risk comes a potentially sustainable process to reclaim otherwise residual waste material. Few studies compare the two residuals. The purpose of this study was to investigate the land application of municipal waste water treatment solids (biosolids) versus manure (broiler and swine) and their effect on pathogens, antibiotic resistance and nutrients.

What did we do?

A 5×4 randomized block design comprised of broiler litter, swine effluent, and municipal biosolids treatments were land applied at a rate of 5-8 tons ha-1 for the broiler litter and biosolids, respectively, while effluent was applied at a rate of 32 ha-cm on a cooperator farm established with forage plots over a three-year period. Swine effluent was applied to the surface or surface-applied then incorporated to approximately 7.5 cm; applications were applied once per season. Soil core samples to 15 cm were collected from plots and were specifically targeted to include waste-residual. Samples were collected in the days, weeks and months following land application. Samples were processed for heterotrophic plate count bacteria, thermotolerant coliforms, enterococci, staphylococci, gram-negative bacteria, Escherichia coli, Clostridium perfringens, Salmonella spp., Campylobacter spp., Listeria monocytogenes, antibiotic resistant bacteria and genes, and 16S rRNA.

What have we learned?

Immediately following land application, most pathogens and indicator bacteria were detected; however, by the end of the first month, most were at background levels. One day following land application (Figure 1), most indicators were noticeably enriched, but following 1 week, levels began to drop to background by week 8 (Figure 2). Pathogens were rarely dependent on waste, for instance, Salmonella was rarely detected, but was detected in both effluent and biosolids-applied plots. Clostridium perfringens, on the other hand was typically found in swine effluent-applied plots, though biosolids-applied plots were also positive for C. perfringens. Campylobacter spp. was not detected at any time point, and E. coli was fleetingly detected. Differences in phenotypic antibiotic resistance weren’t detected, while antibiotic resistance genes were equally detected in most applied treatments. Overall, the influence of waste didn’t alter 1 6S rRNA levels. Microbial ecology, only briefly investigated via terminal restriction fragment length polymorphisms, yielded slight differences between plot treatments. Overall, waste type had a small influence on pathogen/indicator presence and levels following land application, most likely as a result of minimal pathogen levels and application rates such that detection was limited. The overarching results of this study indicate microbial risks associated with any of the tested waste types will be similar, given overall low pathogen levels; however, further investigation into antibiotic resistance, which should be dependent on waste type, will be a focus of interest. Additionally, given the variability of manures, pathogen levels may vary significantly based on region, climate, and concentrated animal feeding operation. Microbial indicators detected

Acknowledgements

The authors would like to thank the work of Cindy Smith, Renotta Smith, Jim Robbins, and our farm and wastewater treatment cooperators.

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

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Abstract

In an effort to assess the off-site transport of bioaerosols, airborne bacteria, fungi, and endotoxin were collected at a 10,000 cow dairy operation. Compared to background locations, the general trend was that bioaerosol concentrations were higher immediately downwind, then decreased with distance from the animal housing. While bioaerosol concentrations did not follow a seasonal trend, they did significantly correlate with meteorological factors such as temperature and solar radiation. Bioaerosol concentrations were also found to be greatest at night, which can be attributed to changes in animal activity and wind speed and reduced exposure of the microorganisms to UV radiation. An analysis of clones generated from air samples collected downwind from the animal housing and pivots spraying dairy wastewater revealed that none of sequence matches were affiliated with bacteria known to be pathogenic to otherwise healthy humans. Results from ongoing research to better understand bioaerosol formation and drift losses during spray irrigation events of dairy wastewater will also be discussed.

Using glass impingers to capture airborne bacteria at a downwind location from a dairy.

Why Study Bioaerosols at Dairies?

Because confinement of cattle increases the microbioal load at dairy production facilities, there are concerns about on-site and off-site exposures to airborne microorganisms and microbial byproducts. The purpose of this study was to monitor concentrations of airborne bacteria, fungi, and endotoxin at a 10,000 cow open-freestall dairy and fields being irrigated with wastewater to assess their potential to be transported off site. This information is important, as inhalation or ingestion of some bioaerosols can be detrimental to health through infection, allergy, or toxicosis.

Open-face filters for capture of airborne endotoxin.

What Did We Do?

Over a one-year period at the dairy, bioaerosols were collected at upwind (background) and downwind sites using glass impingers, direct impaction on media, and a wetted-wall cyclone. Bacteria and fungi were quantified using culture-dependent techniques, while bacteria were also characterized to the genus and species levels by analyzing a region of the 16S ribosomal RNA gene. Airborne endotoxin were captured on filters, then extracted and subsequenetly quantified using the Limulus amebocyte lysate assay.

Wetted-wall cyclone being used to capture bioaerosols for subsequent identification using PCR-based approach.

What Have We Learned?

Compared to background sites, the general trend was that concentrations of airborne bacteria and endotoxin were higher immediately downwind, then decreased with distance from the animal housing. While bioaerosol concentrations did not follow a seasonal trend, they did significantly correlate with meteorological factors such as temperature, wind speed, and solar radiation. Bacteria and endotoxin concentrations were also found to be greatest at night, which can be attributed to changes in animal activity and wind speed and reduced exposure of the microorganisms to UV radiation. Analysis of cloned 16S rRNA genes generated from air samples collected downwind from the animal housing and pivots spraying dairy wastewater revealed that none of sequences were affiliated with bacteria known to be pathogenic to healthy humans.

Future Plans

Conduct a quantitative microbial risk assessment for zoonotic bacterial pathogens in dairy wastewaters that are land applied using center pivot irrigation systems.

Authors

Robert Dungan, Research Microbiologist, USDA-ARS Northwest Irrigation & Soils Research Laboratory, Kimberly, Idaho, robert.dungan@ars.usda.gov

April Leytem, Soil Chemist, USDA-ARS, Kimberly, Idaho

David Bjorenberg, Agricultural Engineer, USDA-ARS, Kimberly, Idaho

Additional Information

Dungan, R.S. and A.B. Leytem. 2009. Airborne endotoxin concentrations at a large open-lot dairy in southern Idaho. J. Environ. Qual. 38:1919-1923.

Dungan, R.S., A.B. Leytem, and D.L. Bjorneberg. 2010. Year-long assessment of airborne endotoxin at a concentrated dairy operation. Aerobiologia. 26:141-148.

Dungan, R.S., A.B. Leytem, S.A. Verwey, and D.L. Bjorneberg. 2010. Assessment of bioaerosols at a concentrated dairy operation. Aerobiologia. 26:171-184.

Dungan, R.S. and A.B. Leytem. 2011. Ambient endotoxin concentrations and assessment of transport at an open-lot and open-freestall dairy. J. Environ. Qual. 40:462-467.

Dungan, R.S., A.B. Leytem, and D.L. Bjorneberg. 2011. Concentrations of airborne endotoxin and microorganisms at a 10,000 cow open-freestall dairy. J. Anim. Sci. 176:426-434.

Dungan, R.S. 2012. Use of a culture-independent approach to characterize aerosolized bacteria at an open-freestall dairy operation. Environ. Int. 41:8-14.

Acknowledgements

Independent Dairy Environmental Action League (IDEAL)

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2013. Title of presentation. Waste to Worth: Spreading Science and Solutions. Denver, CO. April 1-5, 2013. URL of this page. Accessed on: today’s date.

Assessment of Bioaerosol Transport at a Large Dairy Operation from LPE Learning Center