---
title: Methyl red reagent
description: "Methyl red reagent consists of the pH indicator methyl red. This chemical is usually yellow but turns red below pH 4.0. Bacteria exhibiting [mixed acids fermentation](https://vumicro.com/docs/methyl-red-test/) will accumulate acids in the medium, resulting in a color change. Approximately five drops…"
url: "https://vumicro.com/es/docs/methyl-red-reagent/"
updated: "2022-06-17"
category: Reference Library / Reagents, Chemicals, Stains
---

# Methyl red reagent

Methyl red reagent consists of the pH indicator methyl red. This chemical is usually yellow but turns red below pH 4.0. Bacteria exhibiting [mixed acids fermentation](https://vumicro.com/docs/methyl-red-test/) will accumulate acids in the medium, resulting in a color change.

Approximately five drops of methyl red reagent are added to an overnight culture grown in [MRVP broth](https://vumicro.com/docs/mrvp-broth/) to determine the test result.

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