Hit the right concentration

Pick the dilution that lands your culture inside the BactoBox® working range.

Your BactoBox® measures accurately when the vial holds 30 000 to 5 000 000 bacteria-sized objects per mL, cells and particles from your medium alike. Most cultures are far denser than that, so you dilute them first.

When you follow a culture through its growth stages, use this page to pick the dilution for each stage.

Dilute at least 1:100. Most growth media are too conductive to measure at anything less dilute. If you get the error conductivity too high, use 1:201 or more as your lowest dilution. That is 50 µL of sample in 10 mL of diluent.

Pick your dilution

Dilution	When to use it
1:100	Lag, acceleration and early-exponential
1:1 000	Mid- and late-exponential
1:10 000	Deceleration, stationary, and decline
1:100 000 or more	High-density fed-batch fermentations

Dilution schemes

Every result inside the working range is accurate. Each dilution scheme on this page aims for about 1 × 10^6 cells/mL in the vial you measure. That gives fast results with little risk of clogging.

1:100 dilutions

A 1:100 dilution is a single transfer of 101 µL of culture into 10 mL of diluent.

Step by step, with videos

1

Dilute 1:100

Transfer 101 µL of your dispersed sample into a diluent vial and rinse the pipette tip in the vial. Vortex for 10 seconds at maximum speed.

2

Measure

Move the tubing kit to the 1:100 vial and press Measure. Multiply the result by 100.

1:1 000 dilutions

A 1:1 000 dilution takes two steps, 1:100 and then 1:10. Remove 1 mL of diluent from the second vial before you transfer 1 mL from the 1:100 vial into it.

Step by step, with videos

1

Dilute 1:100

Transfer 101 µL of your dispersed sample into a diluent vial and rinse the pipette tip in the vial. Vortex for 10 seconds at maximum speed.

2

Dilute 1:1 000

Remove and discard 1 mL of diluent from a second diluent vial. Transfer 1 mL from the 1:100 vial into it and rinse the pipette tip in the vial. Vortex for 10 seconds at maximum speed.

3

Measure

Move the tubing kit to the 1:1 000 vial and press Measure. Multiply the result by 1 000.

1:10 000 dilutions

A 1:10 000 dilution takes two 1:100 steps.

Step by step, with videos

1

Dilute 1:100

Transfer 101 µL of your dispersed sample into a diluent vial and rinse the pipette tip in the vial. Vortex for 10 seconds at maximum speed.

2

Dilute 1:10 000

Transfer 101 µL from the 1:100 vial into a second diluent vial and rinse the pipette tip in the vial. Vortex for 10 seconds at maximum speed.

3

Measure

Move the tubing kit to the 1:10 000 vial and press Measure. Multiply the result by 10 000.

1:100 000 and higher

Extend the 1:10 000 scheme with a 1:10 step. Remove 1 mL of diluent from a third diluent vial, transfer 1 mL from your 1:10 000 vial into it, rinse the pipette tip in the vial, and vortex for 10 seconds. Repeat for each further factor of 10.