Accelerating the Deactivation of Salmonella enterica Serovar Newport and Escherichia coli O157:H7 in Dairy Manure by Modifying pH or Temperature

John D. Toth*, 1, Helen W. Aceto1, Shelley C. Rankin2, Chitrita DebRoy3, Zhengxia Dou1
1 University of Pennsylvania, School of Veterinary Medicine, Department of Clinical Studies, New Bolton Center, 382 West Street Rd., Kennett Square, PA 19348, USA
2 Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, USA
3 Department of Veterinary and Biomedical Sciences, College of Agricultural Sciences, Pennsylvania State University, 104 Wiley Lab, Wiley Lane, University Park, PA 16802, USA

© 2012 Toth et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Center for Animal Health and Productivity, New Bolton Center, 382 West Street Road, Kennett Square, PA, 19348, USA; Tel: 1-610-925-6327; Fax: 1-610-925-6823; E-mail:


To assess methods for control of disease-causing bacteria in animal manures prior to field application, we manipulated the temperature or adjusted pH of dairy manure to high (3.5 to 5) or low (10 to 12) values with aluminum sulfate or hydrated lime, and inoculated the manure with Salmonella enterica serovar Newport or Escherichia coli O157:H7, then incubated the manure at ambient temperature. At pH ≤4.2, S. Newport was eliminated within 6 days; however at pH >4.2 S. Newport was suppressed only temporarily and recovered to concentrations near the unamended controls. pH required to eliminate E. coli O157:H7 was ≤4.5. Both pathogens were killed by pH ≥11.0. The pathogens were eliminated within 2 weeks when inoculated manure was incubated at 37°C, whereas at 22°C and 4°C, the organisms persisted for much longer periods. S. Newport survived for over 300 days at 4°C, which has implications for manure spreading in colder seasons.

Keywords: Dairy manure, Salmonella, E. coli O157:H7, pathogen deactivation.