title: Selection of in vivo expressed genes of Escherichia coli O157:H7 strain EDL933 in ground meat under elevated temperature conditions.
abstract: Enterohemorrhagic Escherichia coli O157:H7 strains are important foodborne pathogens that are often transmitted to humans by the ingestion of raw or undercooked meat of bovine origin. To investigate adaptation of this pathogen during persistence and growth in ground meat, we  established an in vivo expression technology model to identify genes that are expressed during growth in this food matrix under elevated temperatures (42°C). To improve on the antibiotic-based selection method, we constructed the promoter trap vector pAK-1, containing a promoterless kanamycin  resistance gene. A genomic library of E. coli O157:H7 strain EDL933 was constructed in pAK-1 and used for promoter selection in ground meat. The 20 in vivo expressed genes identified were associated with transport processes, metabolism, macromolecule synthesis, and stress response.  For most of the identified genes, only hypothetical functions could be assigned. The results of our study provide the first insights into the complex response of E. coli O157:H7 to a ground meat environment under elevated temperatures and establish a suitable vector for promoter studies  or selection of in vivo induced promoters in foods such as ground meat.
authors.affiliation: Department of Food Microbiology, Institute of Food Science and Biotechnology, Garbenstraße 28, University of Hohenheim, 70599 Stuttgart, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Kroj
authors.forename: Herbert
authors.initials: H
authors.lastname: Schmidt
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D002417:Cattle; D003257:Consumer Product Safety; D004269:DNA, Bacterial / Q000032:analysis; D019453:Escherichia coli O157 / Q000235:genetics* / Q000254:growth & development; D005506:Food Contamination / Q000517:prevention & control*; D005516:Food Microbiology; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D006358:Hot Temperature; D006801:Humans; D007613:Kanamycin Resistance / Q000235:genetics; D008461:Meat Products / Q000382:microbiology*; D013312:Stress, Physiological
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial