> 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/advanced/measurements-explained/gating/inactivated-bacteria/inactivation-by-alcohol.md). # Inactivation by alcohol Alcohols like 70% ethanol or 70% isopropanol destabilize bacterial lipid membranes into a disordered state that no longer impedes electricity. The conductive cell wall survives the alcohol treatment. {% hint style="info" %} ## Does [BacTotal-10](/advanced/measurements-explained/gating/bactotal-10.md) count alcohol-inactivated bacteria as cells? Mostly not. Once treated with e.g. 70% ethanol or 70% isopropanol, most vegetative bacteria move outside the [BacTotal-10](/advanced/measurements-explained/gating/bactotal-10.md) cell-definition. The alcohol-inactivated populations may be included by custom gating. This is an advanced feature. We only support advanced features through a [custom solution](/advanced/what-is-a-custom-solution.md). [Contact support](/troubleshooting/contact-support.md) for details. {% endhint %} ## Alcohol-inactivated bacteria and [BacTotal-10](/advanced/measurements-explained/gating/bactotal-10.md) The default BactoBox® configuration uses [BacTotal-10](/advanced/measurements-explained/gating/bactotal-10.md). Objects classified as cells are found within the region with lavender shading. The distributions correspond to cultures before (green) and after (red) treatment with 70% isopropanol for 5 min. The plots below are from *Escherichia coli*, *Flavobacterium psychrophilum*, *Klebsiella aerogenes*, and *Salmonella enteritidis*. Alcohol-treatment converts these Gram-negative bacteria to highly conductive objects found outside the [BacTotal-10](/advanced/measurements-explained/gating/bactotal-10.md) cell-definition. Alcohol-inactivated *Salmonella* objects are found in-between the cells and particulates range. Therefore, a proportion of the alcohol-treated *Salmonella* will still be counted, but the cell concentration may be underestimated unless custom gating is used.

Inactivation of Gram-negative bacteria with 70% isopropanol. The untreated cultures (green) are found within the BacTotal-10 cell-definition, while the alcohol-treated cultures (red) are excluded from BacTotal-10.

The electrical changes are similar for Gram-positive bacteria. The plots below are from alcohol-treated cultures of *Bacillus subtilis*, *Clostridium difficile*, *Listeria innocua*, and *Staphylococcus epidermidis*. The alcohol-treated cells are converted to highly conductive objects found outside the [BacTotal-10](/advanced/measurements-explained/gating/bactotal-10.md) cell-definition.

Inactivation of Gram-positive bacteria with 70% isopropanol. The untreated cultures (green) are found within the BacTotal-10 cell-definition, while the alcohol-treated cultures (red) are excluded from BacTotal-10.

## Summary When cells are treated with alcohols like 70% ethanol and 70% isopropanol they move outside the [BacTotal-10](/advanced/measurements-explained/gating/bactotal-10.md) cell-definition. Custom gating is required for BactoBox® to enumerate alcohol-treated cells. {% hint style="info" %} ## Advanced feature 🧩 Custom gating is an advanced feature. We only support advanced features through a [custom solution](/advanced/what-is-a-custom-solution.md). [Contact support](/troubleshooting/contact-support.md) for details. {% endhint %} --- # 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 by asking a question. Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters: ``` GET https://help.sbtinstruments.com/advanced/measurements-explained/gating/inactivated-bacteria/inactivation-by-alcohol.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case. 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.