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“Compost made from livestock manure is commonly used as a crop fertilizer and serves as a possible vehicle for the transmission of Escherichia coli O157:H7 to fresh produce. In this study,
we hypothesized that the indigenous microbial communities present in composts adversely affects the survival of E. coli O157:H7. Escherichia coli O157:H7 was spiked into compost slurry and incubated at 25 °C. Escherichia coli O157:H7 exhibited a c. 4 log10 reduction over 16 days. When compost was supplemented with the eukaryotic inhibitor cycloheximide, there was a minimal decrease in E. coli O157:H7 counts over the same time period. Analysis of microbial communities present in the compost with denaturing gradient gel electrophoresis (DGGE) suggested minor differences in the fungal communities present in cycloheximide-treated compost, compared with untreated compost over a period of 12 days at 25 °C. However, the DGGE profiles Seliciclib purchase of protists showed drastic differences in community complexity. Clone library sequence analysis of protist populations revealed significantly different species composition between treatment and control samples at different time points. This suggests that predation of E. coli O157:H7 by protists might be a potential mechanism for reducing E. coli O157:H7 in compost materials. Enterohemorrhagic Escherichia coli O157:H7 is a deadly foodborne pathogen, with fewer than 50
bacterial cells sufficient to cause diseases such as hemorrhagic colitis and hemolytic uremic syndrome (Kaper et al., 2004). Every year, Dabrafenib supplier approximately 73 000 illnesses occur due to E. coli O157:H7 infections in the United States alone (Rangel et al., 2005). While most cases were attributed to improperly cooked ground beef, an increasing number of cases are associated with the consumption of fresh produce (Sivapalasingam et al., 2004). Cattle are known to be the primary reservoirs of E. coli O157:H7 (Borczyk et al., below 1987). These asymptomatic carriers excrete this pathogen in their feces, and thus cattle manure can serve as a vehicle for pathogen transmission to food products. Previous research has demonstrated that E. coli
O157:H7 survives for long periods of time in a variety of natural environments (Kudva et al., 1998; Jiang et al., 2002; Islam et al., 2004a, b; Scott et al., 2006) including cow manure. Cow manure and composted manure is commonly applied on farm lands as a fertilizer. Improper composting of farm waste can lead to the survival of pathogenic bacteria such as E. coli O157:H7. In order to ensure the safety of compost derived from animal manure, it is imperative to develop science-based composting procedures that minimize the survival of pathogens such as E. coli O157:H7. The present study was designed to identify the class(es) of microorganisms that are antagonistic to E. coli O157:H7 in a cow manure compost slurry model. We determined that one or more members of the protist community negatively affected pathogen survival in our model system.