> For the complete documentation index, see [llms.txt](https://help.sbtinstruments.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.sbtinstruments.com/tutorials/measure-overnight-culture.md). # Measure a dense culture This tutorial is for your second bacterial measurement on BactoBox®. It is slightly more advanced than the first tutorial [Do a simple measurement](/tutorials/measure-vitroid-tm-disc.md) but still simple and predictable with short hands-on time. You will make an overnight culture and learn how to dilute to a suitable working range. The success criterion for this tutorial is to get a BactoBox® measurement within 30,000 to 5,000,000 cells/mL. You can complete this tutorial as a :school\_satchel:Beginner to BactoBox® measurements.

BactoBox® skill level	Time to complete (E. coli)	Hands-on time	Requirements
🎒 Beginner	⏳ 17 hours	⏱️ 0.5 hours	7.6a ≥ v2026.02a Escherichia coli WDCM 00013 Vitroids™

## Soluble *E. coli* Vitroids™ disc For this tutorial we recommend [*Escherichia coli* WDCM 00013 Vitroids™](https://www.sigmaaldrich.com/DK/en/product/sial/vt000137) 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 .

{% hint style="info" icon="snowflakes" %} ## Alternative: Use an in-house *E.coli* cryo stock instead of a Vitroids™ disc You will get the best experience if you procure [*Escherichia coli* WDCM 00013 Vitroids^™](https://www.sigmaaldrich.com/DK/en/product/sial/vt000137) from Sigma/Merck. Alternatively, you can use an in-house *E. coli* glycerol stock to prepare an overnight culture. See more details in [Inoculate LB medium](/tutorials/measure-overnight-culture/inoculate-lb-medium.md). {% endhint %} ## Hit the right concentration An *E. coli* shake flask overnight culture typically has \~1×10¹⁰ cells/mL, i.e. 10,000,000,000 cells/mL. Max concentration for a BactoBox® measurement is 5×10⁶ total/mL, i.e. 5,000,000 total/mL. A typical overnight culture must be diluted 1:10,000 to hit the right concentration. Use two consecutive 1:100 dilution steps to prepare a 1:10,000 dilution.

A 1:10,000 dilution is made by two consecutive 1:100 dilutions.

{% hint style="success" icon="foot-wing" %} ## Save time and reagents by using 1:100 dilutions instead of 1:10 dilutions BactoBox® has a \~100-fold [dynamic range](#user-content-fn-1)[^1]. You save time and reagents by using 1:100 dilutions. This is different from the 1:10 dilution series used in microbiology. The 1:10 dilutions are needed for plate counts where the dynamic range is only 10-fold (25–250 colonies are typically counted on an agar plate). {% endhint %} ## Overview In this tutorial we will demonstrate how to solubilize the disc and get the bacteria ready for BactoBox® analyses. The overall steps in the tutorial are given below. 1. [Get things ready](/tutorials/measure-overnight-culture/get-things-ready.md) 2. [Inoculate LB medium](/tutorials/measure-overnight-culture/inoculate-lb-medium.md) 3. [Prepare sample](/tutorials/measure-overnight-culture/disaggregate-bacteria.md) 4. [Dilute and measure](/tutorials/measure-overnight-culture/dilute-and-measure.md) 5. [Summary](/tutorials/measure-overnight-culture/summary.md) ## Summary After this introduction you can proceed to [Get things ready](/tutorials/measure-overnight-culture/get-things-ready.md). [^1]: Dynamic range is the interval over which a method provides reliable quantitative measurements. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://help.sbtinstruments.com/tutorials/measure-overnight-culture.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.