Check lowest culture

After removing irrelevant cultures, it's time to measure the concentration of the remaining overnight cultures. Begin with the culture having the lowest turbidity, which in this case is the vial -8 . We will use a 1:1 000 dilution in two sequential dilution steps: An initial 1:100 dilution followed by a additional 1:10 dilution.

1

Disaggregate cell clumps

Vortex the vial 1 minute at maximum speed to disaggregate cell clumps. See Break up clumps and chains if your bacterium needs more aggressive disaggregation.

2

Dilute 1:100

Transfer 101 µL of your sample to 10 mL of diluent. Vortex 10 seconds at maximum speed.

3

Dilute 1:1 000

Remove 1 mL diluent from a 10 mL diluent vial for a residual volume of 9 mL.

Transfer 1 mL of the 1:100 dilution to the this vial. Vortex 10 seconds at maximum speed.

4

Measure on the diluted sample

Transfer the tubing kit to the 1:1 000 vial.

Press Measure in Access to start a new measurement.

• Dilution: 1 000

• Label: overnight_-8

Summary

Of the remaining vials, the culture with the lowest turbidity has a concentration of 1.4 × 10⁹ cells/mL. Next, we will check remaining cultures to identify the culture that has just reached onset of stationary phase.