Track growth curve

TUT-3: Your first growth curve tracked with BactoBox®

This tutorial will teach you how to track a bacterial growth curve using BactoBox® as a stand-alone device.

You should plan for approximately 4 hours of hands-on work and a total duration of 12 hours to complete the full growth curve experiment. During the first 5 hours, most of the time will be spent waiting for the culture to reach a suitable concentration.

The first step is straightforward. To make your workday more efficient and avoid a long day in the lab, consider asking a colleague who arrives early to inoculate the culture before you begin.

Complete tutorial and first

Before starting this tutorial, first complete the Do a simple measurement and Measure a dense culture. They are simpler and faster. The present tutorial is slightly more complex.

The goal of this tutorial is to generate a high-quality BactoBox® growth curve that enables reliable determination of the growth rate.

This tutorial is suitable for 🎒Beginners and can be completed without prior experience using BactoBox® for growth measurements.

BactoBox® skill level	Time to complete (E. coli)	Hands-on time	Requirements
🎒 Beginner	⏳ 12 hours	⏱️ 4 hours	7.6a ≥ v2026.02a Escherichia coli WDCM 00013 Vitroids™

E. coli Vitroids™ disc

We recommend Escherichia coli WDCM 00013 Vitroids™ ATCC^® 25922 from Sigma/Merck. Lead time is usually 1-5 days. Price is ~200 USD including shipping. 10 vials are included in each shipment. Concentration per disc is stated as 50,000-150,000 CFU mean value range.

A soluble Vitroid™ disc containing 50,000–150,000 CFU of E. coli ATCC® 25922 .

Alternative: Use an in-house E.coli glycerol stock instead of a Vitroids™ disc

For the best experience, we recommend using Escherichia coli WDCM 00013 Vitroids^™ from Sigma/Merck. Alternatively, you can prepare an overnight culture from an in-house E. coli glycerol stock. For detailed preparation instructions, see Inoculate LB medium.

Hit the right conductivity

The conductivity must be within the range of 1,500–2,200 µS/cm to be measured with BactoBox®. A 1:100 dilution is typically sufficient to achieve the required conductivity.

For most growth media, undiluted cultures and 1:10 dilutions have a conductivity that exceeds the acceptable range. If such samples are measured, BactoBox® will display a conductivity error.

Conductivity measurements for a dilution series of the growth medium. Dilutions of 1:100, 1:1,000, 1:10,000, and 1:100,000 all fall within the accepted conductivity range of 1,500–2,200 µS/cm. In contrast, the undiluted growth medium and the 1:10 dilution exceed the acceptable conductivity range.

Dilute at least 1:100 to hit the right conductivity.

Most growth media must be diluted at least 1:100 to reach the conductivity range required for BactoBox® measurements (1,500–2,200 µS/cm).

Pre-incubate culture 5 hours before measurements

The culture must be incubated before its cell concentration can be measured using BactoBox®.

Once dissolved in 50 mL of growth medium, the Vitroids™ disc yields a cell concentration of approximately 1,000 CFU/mL. Based on experience, the culture typically requires around 5 hours of incubation before the cell concentration becomes detectable with a 1:100 dilution.

Change dilution factors as the concentration increases

Begin the measurements using a 1:100 dilution. As the cell concentration increases, use higher dilution factors, such as 1:1,000 and 1:10,000. The following subpages will guide you through each step.

Overview

The overall steps in the tutorial are given below.

1. Get things ready

2. Inoculate LB medium

3. Prepare sample

4. 1:100 dilutions

5. 1:1,000 dilutions

6. 1:10,000 dilutions

7. Data analysis

8. Summary

Summary

After this introduction you can proceed to Get things ready.