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Title:   Author  item
                                            DUOSS, HEATHER - Mississippi State Universityitem
                                            SCHMIDT, TY - Mississippi State Universityitem
                                            Callaway, Todditem
                                            Carroll, Jeffery

                                                         - *Jeff Carroll*item
                                            MARTIN, JAMES - Mississippi State Universityitem
                                            SHIELDS-MENARD, SARA - Mississippi State Universityitem
                                            BROADWAY, PAUL - Mississippi State Universityitem
                                            DONALDSON, JANET - Mississippi State University
  Submitted to: International Journal of Microbiology
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 1/8/2013
                                    Publication  Date: 7/15/2013
                                    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.


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