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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Environmental Microbial & Food Safety Laboratory » Research » Publications at this Location » Publication #311009
Title: Survival of Salmonella spp. in dried turkey manure and persistence on spinach leaves

Author
item ONI, RUTH - University Of Maryland
item Sharma, Manan
item BUCHANAN, ROBERT - University Of Maryland

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/28/2015
Publication Date: 10/1/2015
Citation: Oni, R., Sharma, M., Buchanan, R.L. 2015. Survival of Salmonella spp. in dried turkey manure and persistence on spinach leaves. Journal of Food Protection. 78:1791-1799.

Interpretive Summary: Salmonella spp. has been the cause of several major outbreaks in the U.S. related to the consumption of produce commodities (leafy greens, peppers, tomatoes, sprouts, etc.). One route of contamination by Salmonella of leafy green crops may be through the dispersal of manure dust from adjacent animal livestocking operations. Livestock animal manure is known to harbor bacterial pathogens like Salmonella; therefore, dust generated from these facilities may contaminate produce commodities. We show is this study that low moisture content (5%) and small particle size (125 'm) of the manure dust enhanced the survival of Salmonella on spinach leaves of growing plants. Futhermore, Salmonella in manure dust was more protected from inactivation by ultra-violet light (simulated sunlight) in a greenhouse than when no manure was present. The results of this study suggest that Salmonella spp. in aerosolized, dry, small manure particles can contaminate leafy greens, and that the presence of the manure dust allows for pathogens to survive for longer durations on spinach plants. This information will be useful to other scientists and to the produce industry.

Technical Abstract: Concerns about the microbiological safety of fresh produce has attracted attention in the past three decades due to multiple foodborne outbreaks. Animal manure contaminated with enteric pathogens has been identified as an important pre-harvest pathogen source. This study investigated the survival of Salmonella enterica in dust particles of dehydrated turkey manure, and how manure dust could potentially serve as an airborne vehicle leading to the contamination of leafy greens in the field. The survival of an inocula of multiple Salmonella serotypes in the dried fecal material of various particle sizes (125, 212, 355 and 500 µm) was examined at varying moisture contents (5, 10, 15%). Results obtained showed that survival times were inversely related to moisture content and particle size of manure dust, with viable Salmonella still detectable for up to 291 days in the smallest particle size (125µm) with 5% moisture. Association with manure dust particles increased the survival of Salmonella when subjected to UV light both under laboratory conditions and on the surface of spinach leaves in a greenhouse setting. The results of this study suggest that aerosolized manure particles could be a potential vehicle for Salmonella airborne dispersal to leafy greens if the microorganism is present in the dry manure.