title: Survival of Escherichia coli O157:H7 transformed with either the pAK1-lux or pXEN-13 plasmids in in vitro bovine ruminal and fecal microbial fermentations.
abstract: The use of luminescent plasmids in bacteria may serve as a viable model for the real-time validation of various pre-harvest interventions on the colonization or shedding patterns of Escherichia coli O157:H7 within cattle. The objective of this study was to determine if the growth characteristics of E. coli O157:H7 in mixed ruminal and fecal microbial fluid cultures would be altered when transformed with one of the two luminescent plasmids: pAK1-lux (PAK) or pXEN-13 (XEN). Transformants harboring the luminescent plasmids were compared to the non-transformed parental strain (wild type [WT]) after incubating in mixed ruminal or fecal microbial fluid media for 6 h in triplicate (n=3). The transformants and WT exhibited similar growth rates. Within mixed ruminal microbial fluid fermentations and mixed fecal microbial fluid, all transformants grew similarly (p=0.28) through the 6-h study. The reflective light unit (RLU; photons/pixel per second) photonic emissions of each plasmid within ruminal fluid differed at 0 h (p=0.002) and 2 h (p=0.02) and within fecal fluid at 0 h (p=0.009) and 2 h (p=0.04). The RLU remained the same within rumen fluid at 4 h (p=0.22) and 6 h (p=0.80) and within fecal fluid at 4 h (p=0.06) and 6 h (p=0.29). Growth of E. coli O157:H7 transformed with the bioluminescent plasmids was not altered in comparison to the WT, suggesting that both plasmids may serve as useful models for in vivo studies.
authors: Department of Animal and Dairy Sciences, Mississippi State University, Mississippi State, MS, USA.
authors: Heather A
authors: HA
authors: Duoss
authors: Janet R
authors: JR
authors: Donaldson
authors: Todd R
authors: TR
authors: Callaway
authors: Jeffery A
authors: JA
authors: Carroll
authors: Paul R
authors: PR
authors: Broadway
authors: James M
authors: JM
authors: Martin
authors: Sara
authors: S
authors: Shields-Menard
authors: Ty B
authors: TB
authors: Schmidt
mesh_terms: D000818:Animals; D057138:Bacterial Shedding; D001826:Body Fluids; D002417:Cattle; D015169:Colony Count, Microbial; D019453:Escherichia coli O157 / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D005243:Feces / Q000382:microbiology*; D005260:Female; D005285:Fermentation; D005819:Genetic Markers; D049449:Luminescence; D008297:Male; D010957:Plasmids / Q000235:genetics*; D012417:Rumen / Q000382:microbiology*; D014170:Transformation, Genetic
chemical_list: D005819:Genetic Markers