MRS Broth Test- Principle, Procedure and Results


MRS Broth Test is a microbiological test that is used to identify and enumerate lactobacilli in various samples. Lactobacilli are gram-positive, rod-shaped bacteria that are widely distributed in nature and are involved in many fermentation processes. They are also part of the normal flora of the human gastrointestinal tract and vagina, and have beneficial effects on health and immunity. Some lactobacilli are also used as probiotics, starter cultures, or bio-preservatives in food and dairy industries.

The MRS Broth Test is based on the ability of lactobacilli to grow and ferment glucose in a selective medium that contains various nutrients and inhibitors. The medium, known as MRS Broth or De Man, Rogosa and Sharpe Broth, was developed in 1960 by De Man et al. to enhance the growth of fastidious lactobacilli that were difficult to cultivate on other media. The test can be performed on pure cultures or mixed samples, such as milk, cheese, yogurt, wine, beer, silage, feces, etc.

The objectives of the MRS Broth Test are:

  • To cultivate and enumerate lactobacilli in a laboratory setting
  • To determine the ability of lactobacilli to form gas during glucose fermentation
  • To differentiate lactobacilli from other bacteria based on their growth and gas production patterns

The MRS Broth Test is a simple, reliable, and inexpensive method to identify and quantify lactobacilli in various samples. It can be used for quality control, research, or diagnostic purposes. However, it also has some limitations and requires confirmation by other biochemical or molecular tests. In this article, we will explain the principle, procedure, results, limitations, and quality controls of the MRS Broth Test in detail.