Manure Source and Age Affect Survival of Zoonotic Pathogens during Aerobic Composting at Sublethal Temperatures

Abstract

Heat is the primary mechanism by which aerobic composting inactivates zoonotic bacterial pathogens residing within animal manures, but at sublethal temperatures, the time necessary to hold the compost materials to ensure pathogen inactivation is uncertain. To determine the influence of the type of nitrogen amendment on inactivation of Salmonella, Listeria monocytogenes, and Escherichia coli O157:H7 in compost mixtures stored at sublethal temperatures, specific variables investigated in these studies included the animal source of the manure, the initial carbon/nitrogen (C:N) ratio of the compost mixture, and the age of the manure. Salmonella and L. monocytogenes were both inactivated more rapidly in chicken and swine compost mixtures stored at 20°C when formulated to an initial C:N ratio of 20:1 compared with 40:1, whereas a C:N ratio did not have an effect on inactivation of these pathogens in cow compost mixtures. Pathogen inactivation was related to the elevated pH of the samples that likely arises from ammonia produced by the indigenous microflora in the compost mixtures. Indigenous microbial activity was reduced when compost mixtures were stored at 30°C and drier conditions (<10% moisture level) were prevalent. Furthermore, under these drier conditions, Salmonella persisted to a greater extent than L. monocytogenes, and the desiccation resistance of Salmonella appeared to convey cross-protection to ammonia. Salmonella persisted longer in compost mixtures prepared with aged chicken litter compared with fresh chicken litter, whereas E. coli O157:H7 survived to similar extents in compost mixtures prepared with either fresh or aged cow manure. The different responses observed when different sources of manure were used in compost mixtures reveal that guidelines with times required for pathogen inactivation in compost mixtures stored at sublethal temperatures should be dependent on the source of nitrogen, i.e., type of animal manure, present.

Survival and Persistence of Foodborne Pathogens in Manure-Amended Soils and Prevalence on Fresh Produce in Certified Organic Farms: A Multi-Regional Baseline Analysis

“…in ruminants and poultry, but horse samples tested positive only for L. monocytogenes. These findings are in agreement with other studies that also reported a wide range of foodborne pathogen prevalence which was associated with the animal manure source (e.g., species, season, diet and husbandry, intermittent shedding in natural reservoirs) and type of feedstocks/bedding used (Hutchison et al, 2004;Ingham et al, 2005;Jay et al, 2007;Sinton et al, 2007;Moriarty et al, 2011;Berry et al, 2013;Erickson et al, 2014Erickson et al, , 2015. Variation in management practices among the farms may reflect the spatial-temporal clustering of positive samples, highlighting the importance of surveying multiple farms and conducting multi-year studies.…”

Assessment of Pathogen Inactivation under Sub-composting Temperature in Lab-scale Compost Piles

“…The factors such as feedstock type, carbon to nitrogen ratio, weather conditions, and mixing of the compost piles influence the temperature of compost piles and the quality of compost (Erickson et al, 2015;Sakthivadivu, Sivakumar, Kumar, & Natarajan, 2015;Yang et al, 2015). While composting swine manure with rice straw, Zhu (2007) observed that it took 5.1 hr and 3.6 hr to reach the bin temperature of 55 º C, when the C: N ratios were 20 and 25, respectively.…”

“…Another study by Shepherd, Liang, Jiang, Doyle & Ercikson (2007) reported that E. coli survived 14 days in dairy manure pile during composting [temperature of the pile was 50 º C]. The survival of E. coli in dairy cow manure was extended to 6 weeks when the composting pile temperature was kept constant at 30 ºC (Erickson, Smith, Jiang, Flitcroft, & Doyle, 2015).…”

Biowastes of slaughterhouses and wet markets: an overview of waste management for disease prevention

“…(2.6×10 4 CFU) and a significant reduction in the viable counts of Listeria sp. (1.7×10 4 CFU) • Nitrogen was shown efficient for the inactivation of Salmonella , Listeria sp., and Escherichia coli in animal manure Goberna et al ( 2011 ) Erickson et al ( 2015 ) Dairy manure • Ammonia inactivated pathogens ( Salmonella spp., L. monocytogenes , and E. coli ) faster in fresh manure compared with aged manure Erickson et al ( 2014 ) Animal waste feedstock • Pathogens can be inactivated through heat and microbial competition during the composting process Gurtler et al ( 2018 ) …”