Assessing Phage-Mediated Bacterial Growth Inhibition Using Optical Density Measurements

Begin with a multiwell plate containing a serially diluted phage suspension in nutrient-rich broth as the treatment and phage-free broth as the control.

Add E. coli to each well. Using a spectrophotometer, measure the baseline optical density (OD) to record the initial bacterial concentration.

Next, incubate the plate to allow bacterial growth and phage infection.

In the control, bacteria utilize nutrients and proliferate, increasing OD.

In the treatment, phages bind to bacterial surface receptors and inject their genomes into the cytoplasm.

Using the host cell machinery, the viral genome replicates and produces viral proteins, which assemble into new virus particles. These particles lyse the cell, releasing progeny.

Measure OD at intervals to compare bacterial growth.

Control wells show a progressive increase in OD, while phage-treated wells exhibit lower OD values, with greater reductions at higher phage concentrations.

This helps determine the phage concentration required for maximum bacterial growth inhibition.

To begin with, set up the microplate assay using filtered tips to avoid cross contamination. First, add 180 microliters of mTSB in the wells of columns one to 12 of the 96-well m