Preparing a Soil Bacterial Culture for Bacteriophage Infection

Begin with a culture plate containing isolated colonies of a soil bacterium.

Pick and inoculate a colony into a baffled culture flask containing a nutrient medium.

Incubate the culture with shaking.

The baffled flask has internal ridges that increase turbulence during shaking, enhancing aeration.

This process ensures uniform oxygen distribution and prevents cell clumping and sedimentation, allowing even nutrient dispersal.

The bacteria proliferate rapidly, forming a dense suspension with cells that exhibit uniform physiological characteristics.

At regular intervals, collect a sample in a cuvette.

Using a spectrophotometer, pass light through the sample. The amount of transmitted light is measured to quantify bacterial growth, known as optical density or OD.

Select bacterial cultures in the exponential to early stationary phase, since cells at this stage are highly metabolically active and therefore most susceptible to efficient bacteriophage infection.

Arthrobacter cells are cultured from colonies streaked on an LB agar plate, incubated at 30 degrees Celsius for two to three days.

Use a sterile loop to pick a colony and add it to 50 milliliters of LB broth in a baffled culture flask. Incubate the flask in a shaking incubator at 225 rpm at 30 degrees Celsius for approximately 24 hours to obtain exponential or early stationary phase cells for phage infection experiments.

Monitor the state of bacterial growth closely to prevent cells from entering the middle to late stationary growth state. The ideal OD₆₀₀ for phage isolation is between 0.5 and 0.7.