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United States Department of Agriculture

Agricultural Research Service

Research Project: INTERVENTIONS TO REDUCE FOODBORNE PATHOGENS IN SWINE AND CATTLE

Location: Food and Feed Safety Research

Title: Effect of citrus byproducts on survival of O157:H7 and non-O157 Escherichia coli serogroups within in vitro bovine ruminal microbial fermentations

Authors
item Duoss, Heather -
item Schmidt, Ty -
item Callaway, Todd
item Carroll, Jeffery
item Martin, James -
item Shields-Menard, Sara -
item Broadway, Paul -
item Donaldson, Janet -

Submitted to: International Journal of Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 8, 2013
Publication Date: July 15, 2013
Repository URL: http://handle.nal.usda.gov/10113/58271
Citation: Duoss-Jennings, H.A., Schmidt, T.B., Callaway, T.R., Carroll, J.A., Martin, J.M., Shields-Menard, S.A., Broadway, P.R., Donaldson, J.R. 2013. Effect of citrus byproducts on survival of O157:H7 and non-O157 Escherichia coli serogroups within in vitro bovine ruminal microbial fermentations. International Journal of Microbiology. 2013:Article 398320. doi: 10.1155/2013/398320.

Interpretive Summary: Bovine ruminal fluid can contain E. coli O157 and other pathogenic bacteria. Citrus by-products contain essential oils that possess antimicrobial activities that can exert damage to the cell wall of gram-negative bacteria, such as E. coli. Inclusion of citrus by-products (CBP) in the diets of cattle has been reported to alter the rumen and intestinal gram-negative microbial populations. This alteration to gram-negative microbes has resulted in CBP being investigated as a potential pre-harvest pathogen intervention strategy to reduce Shiga toxin-producing Escherichia coli (STEC) populations. Therefore, our hypothesis was that CBP might decrease STEC populations with varying degrees between non-O157 STEC serogroups when cultured within ruminal microbial fermentations (RMF). CBP decreased populations of O103:H8 O157:H7 delta-stx1 stx2, and O103:H8 in the presence of >5% powdered CBP, but not other STECs. Further research is needed to determine how the various STEC survive within RMF when supplemented with CBP.

Technical Abstract: Citrus by-products contain essential oils that possess antimicrobial activities that can exert damage to the cell wall of gram-negative bacteria. This alteration to gram-negative microbes has resulted in CBP being investigated as a potential pre-harvest pathogen intervention strategy to reduce Shiga toxin-producing Escherichia coli (STEC) populations. Although CBP research has been conducted utilizing O157:H7, there is limited knowledge as to the effect, if any, that CBP may have on the viability of other Shiga toxin-producing E. coli (STEC) serogroups. Traditionally, researchers have believed that non-O157 serogroups grow similarly to O157:H7. However, a study recently conducted within our group suggests that the responses of these non-O157 serogroups are not universal. Therefore, our hypothesis was that CBP might decrease STEC populations with varying degrees between non-O157 STEC serogroups when cultured within ruminal microbial fermentations (RMF). Variations were apparent in the populations of the various STEC (log10 CFU/mL) within RMF supplemented with CBP. CBP decreased populations of O103:H8 and O157:H7 dealta-stx1 stx2, O103:H8 approximately 1 log10 CFU/ml reduction over the 6 h study in the presence of >5% powdered CBP. When 10% and 20% powdered CBP was added to the RMF, populations of O157:H7 dealta-stx1 stx2 decreased by 1.5 log10 and 5 log10 CFU/ml, respectively. Although our research has reported a decrease in pH values with increasing CBP concentrations and an observed decrease in O103:H8 and O157:H7 delta-stx1stx2 populations, this trend was not observed in other STEC. Further research is needed to determine how the various STEC survive within RMF when supplemented with CBP.

Last Modified: 9/22/2014