Development of a Microtiter Plate Assay for Real Time Analysis of T7 Bacteriophage Mediated Lysis of Escherichia coli

When stressed, Escherichia coli releases soluble factors such as outer membrane vesicles. The release of these factors in the extracellular milieu has been shown to prevent bacteriophage infection in some cases. In this project, we developed an assay to study the effects of soluble factors on T7 bacteriophage infection of Escherichia coli. Our approach used a 96 well plate approach as an efficient alternative to plaque assays for monitoring phage infection of Escherichia coli based on optical density. Media taken from cultures of Escherichia coli mutants expected to show varied levels of outer membrane vesicle secretion were added to untreated wild-type Escherichia coli to test for resistance against T7 bacteriophage in a 96 well plate assay. Optical density decline of Escherichia coli treated
with spent media from UB1005 and the four mutant strains were delayed compared the untreated Escherichia coli control. Taken together, these results implicate a protective effect due to the addition of spent media. We have successfully established a cost efficient and time-saving assay using a 96 well plate to track bacteriophage infection of bacterial cells.