Purpose: To characterize phage specific to Salmonella and Escherichia coli from water samples in the Southeastern Michigan and to develop a novel bacteria detection method using phage.
Methods: Environmental water samples were collected from rivers and waste water treatment plant (WWTP) in Southeastern Michigan. E. coli and Salmonella phage were isolated from water samples using a soft agar overlay technique with multiple indicator strains. Host range of phage was determined using 18 Salmonella strains and 14 E. coli strains. Transmission Electron Microscopy (TEM) was used to visualize the morphology of representative phage. Tailspike Protein (TSP) from E. coli O157 phage ФV10 was functionalized on a graphene field-effect-transister (FET). The binding of TSP and E. coliO157 was measured by the shift of Dirac Point.
Results: A total of 70 Salmonella phage and 33 E. coli phage were purified. Twelve E. coli phage were able to grow in E. coli O157. All Salmonella phage comprising of 37 host range patterns were able to multiply in 3 or more indicator strains. Out of 9 host range patterns observed in E. coli phage, 6 patterns of phage were able to multiply in 3 or more indicator strains. This suggests a broad host range of the phage recovered. TEM demonstrated tail structures in most E. coli phage and Salmonella phage tested. Detectable conductance change was observed when E. coli O157 binds to TSP-functionalized graphene FET whereas Salmonella binding only caused very small shift in Dirac Point, indicating high specificity of E. coli O157 interaction with the TSP.
Significance: Phage with broad host ranges are prevalent in water. Phage TSP has the potential to be applied to bacteria detection.