O16 Antigen Confers Resistance to Bacteriophage T4 and T7 But Does Not Reduce T4/T7 Adsorption in Escherichia coli K-12.

SUMMARY Expression of O16 antigen in MG1655 Escherichia coli K-12 was previously shown to be sufficient to confer resistance to T4 bacteriophage mediated cell-lysis. It was further demonstrated that O16 antigen confers resistance against T4 bacteriophage by preventing adsorption. The main purpose of this research project is to test whether these findings can be replicated with a different bacteriophage, T7. Two Escherichia coli K-12 substrains were used in this experiment; MG1655, which does not produce O antigen, and its isogenic strain, DFB1655 L9, which produces O16 antigen via rescue of the wbbL gene. These strains were isolated and identities confirmed via colony PCR. T4 and T7 phage lysates were generated and the identities confirmed by PCR. Susceptibility to T4/T7 infection was tested by growth curve analysis and double agar overlay plaque assay. An adsorption assay with qPCR analysis was performed to test for differential bacteriophage adsorption between MG1655 and DFB1655 L9. Our results indicate that DFB1655 L9 is resistant to both bacteriophages, suggesting that O16 antigen is sufficient to confer resistance against T4 and T7 mediated cell lysis. However, contrary to previous findings, we did not observe any difference in adsorption between MG1655 and DFB1655 L9 for either T4 or T7.