1 Creation of a Recombinant Bacteriophage to Express Beta-Galactosidase Catherine Swedberg & Heather Talbott with Dr. John Willford Department of Microbiology and Molecular biology University of Wyoming
2 Food-borne illness Pathogens such as Escherichia coli, Salmonella, Listeria, and Camplyobacter are a major cause of food-borne illness Estimated that there are 9.4 million cases of food-borne illness in the USA annually 55,961 hospitalizations annually 1,351 deaths annually (Center for Disease Control, 2011) Huge impact on public safety and economic impact on food industry
3 Current Methods of DetectionCurrent methods detecting pathogens in food use several techniques Classic microbiological methods Serological methods (ELISA) Genetic methods (PCR) Potential issues Long detection time Labor intensive process Lack of sensitivity
4 Bacteriophage Viruses that infect bacteria Very host specificBind to receptors on host cell membrane Can be used for detection of bacteria
5 Reporter Phage Reporter phage have successfully detected bacteria such as Listeria monocytogenes, Staphylococcus aureus, Escherichia coli O157:H7 and Salmonella spp. Reporter Genes used: Luciferase (lux) genes Ice nucleation (inaW) genes Beta-galactosidase (lacZ) genes
6 Lytic Cycle in Wild Type
7 Lytic Cycle after recombination
8 Previous Reporter Phage StudyReporter phage with lacZ inserted into uvsY gene uvsY gene is responsible for DNA replication, repair, and recombination An essential gene Found reporter phage had longer replication times and severely reduced burst size Wild type 132 virus burst size Reporter phage 4 virus burst size Utilized in the Phast Swab Detection System with moderate success (Willford & Goodridge, 2008)
9 Project Objections Fix problems associated with the previous studyChoose a non-essential gene to insert the reporter gene Create plasmid based on new reporter insertion design Produce new reporter phage
10 Beta-galactosidase Beta-galactosidase Easy to measureStable in cell lysates Previously used to construct successful reporter phage Easy to measure 3 substrates may be used Colormetric Luminescent Fluorescent Colormetric substrate, X-gal, was used
11 Reporter Phage ConstructionBacteriophage T4K10 is already denA- and denB- Both are non-essential genes Selected denA as insertion site Gene 22 promoter Late, strong promoter Lots of protein production
12 Created in Previous WorkpDen6 Plasmid containing the denA gene pEF25 Plasmid containing the P22::lacZ gene fusion Need to excise the fusion and insert it into the denA gene
13 Plasmid Creation pDen6 cut with SnaBI pEF25-75 cut with BsrBI and SmaI800 bp with P22::lacZ fusion ligated into cut pDen6
14 Plasmid Results Ligation was transformed into E. coli HB101Plasmid preps run on a gel up-shift from pDen6 present
15 Reporter Gene ConfirmationMultiplex PCR with DenAF, DenAR, p22F, and lacZR primers Awaiting sequencing confirmation
16 Future Research Successfully introduce reporter gene into T4K10 bacteriophage Re-run Phast Swab Assay with new reporter phage
17 Acknowledgements Dr. Gerry Andrews MOLB DepartmentKaren White INBRE Undergraduate Research Program Dr. John Willford
18 Thank you! ? ? ? ? ? ? Questions…. ? ? ?