# High-quality culture
{% hint style="info" %}
**Your perspective on this concept matters**
As you read, notice whether the ideas make sense in your context and feel relevant to your work. You can share your reflections using the feedback instructions at the end of the page.
{% endhint %}
## Key takeaways
* **A high-quality culture** is one where total cell counts and CFU/mL agree within a practical tolerance (e.g. ±25%).
* **When CFU/mL and direct cell counts align,** it means that all cells in a culture are viable.
* **Poor-quality cultures** occur when total direct cell counts are higher than CFU/mL, often in late stationary or death phase.
* Non-culturable cells can still influence experiments or affect downstream propagation, so cultures with misaligned counts add uncertainty and risk.
## What we mean by high-quality culture
A high-quality culture is one in which all cells are able to form colonies on solid agar under your defined plating protocol. In other words, BactoBox cells/mL and plate CFU/mL align within an agreed tolerance at the time of use. We suggest adopting a practical window such as ±25 percent to account for variability in the plating technique.
## Why high-quality cultures matter
When BactoBox cells/mL\[1] and CFU align, you remove ambiguity about the state of the cells you are working with. In contrast, a culture is of poor quality when BactoBox cells/mL and CFU do not align, most commonly with cells/mL results being significantly higher than CFU/mL. This commonly occurs in late stationary or death phase, i.e. when a fraction of the cell population is stressed, dormant, injured, dead, or perhaps temporarily non-culturable under the plating conditions. Failure to form colonies does not prove cell death\[2]. Such cells may still proliferate in liquid culture or interact with your system. Because their behavior is uncertain, these mixtures add noise and risk to experiments or subsequent growth dynamics and can confound interpretation of results.
{% hint style="info" %}
## Give feedback
Your feedback is especially valuable on this page.\
Share your thoughts using the options on the right.
{% endhint %}
***
\[1] Using the default gating setting “BacTotal-v2024-10”
\[2]
---
# Agent Instructions: 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:
```
GET https://help.sbtinstruments.com/mpd/encyclopedia/high-quality-culture.md?ask=
```
The question should be specific, self-contained, and written in natural language.
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.