Location: Food and Feed Safety Research
Title: Effects of Nitrate Or Nitro-Supplementation, with Or Without Added Chlorate, on Salmonella Enterica Serovar Typhimurium and Escherichia Coli in Swine Fecal Incubations Authors
|Jung, Yong Soo|
|Oliver, Christy - NDSU, FARGO ND|
Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 19, 2006
Publication Date: February 1, 2007
Citation: Anderson, R.C., Jung, Y., Oliver, C., Horrocks, S.M., Genovese, K.J., Harvey, R.B., Callaway, T.R., Edrington, T.S., Nisbet, D.J. 2007. Effects of nitrate or nitro-supplementation, with or without added chlorate, on Salmonella enterica serovar Typhimurium and Escherichia coli in swine feces. Journal of Food Protection. 70:308-315. Interpretive Summary: An experimental feed additive containing chlorate as its active ingredient has shown considerable promise in reducing numbers of foodborne pathogenic bacteria such as Salmonella and E. coli in food producing animals. In this study, we tested the effects of another chlorate-acting like chemical, whether alone or combined with chlorate, on the Salmonella- and E. coli-killing ability of the chlorate ingredient in suspensions of gut bacteria obtained from pigs. Our results confirmed that the chlorate ingredient exhibits significant Salmonella- and E. coli-killing ability, reducing numbers of these bacteria more than 100-fold as compared to numbers found in control suspensions containing no added test chemical. Our results also showed that combining the chlorate-acting like chemical with chlorate significantly enhanced Salmonella- and E. coli-killing. When we tested several other different chemical combinations with chlorate, we again observed significantly enhanced Salmonella- and E. coli-killing and that two of these chemicals, officially named 2-nitro-1-propanol and 2-nitroethanol, exhibited Salmonella- and E. coli- killing activity even without added chlorate. These results provide valuable information that will help us develop new and improved microbiological control strategies to rid pathogenic bacteria from food producing animals. Ultimately, this research will help farmers and food processors more efficiently produce safe and wholesome food products for the American consumer.
Technical Abstract: The effects of co-incubating the active agent of an experimental chlorate product with nitrate or select nitrocompounds, possible inducers and competing substrates for the targeted respiratory nitrate reductase, on concentrations of experimentally inoculated Salmonella enterica serovar Typhimurium and wildtype E. coli were determined in swine fecal suspensions. Results confirmed the bactericidal effect of chlorate (5 to 10 mM) against these enterobacteria, reducing (P < 0.05) concentrations > 2 log10 CFU by 3 to 6 h after incubation. An effect (P < 0.05) of pH was observed, with considerable regrowth of Salmonella and E. coli occurring after 24 h incubation in suspensions buffered to pH 7.1 but not in suspensions buffered to pH 6.5 or 5.6. After 24 h co-incubation of suspensions with 5 to 10 mM chlorate and as little as 2.5 mM nitrate or 10 to 20 mM 2-nitro-1-propanol, 2-nitroethanol and sometimes, nitroethane, lower (P < 0.05) Salmonella, but not necessarily E. coli concentrations were observed, with the lack of effect for E. coli possibly obscured by a less sensitive limit of detection (100 versus 10 CFU mL**-1). 2-Nitro-1-propanol and 2-nitroethanol in their own right exhibited inhibitory activity against Salmonella and E. coli by as yet an undetermined mechanism.