E. coli determination (Solid Environment)

E. coli Determination (Solid Medium)
E. coli Determination (Solid Medium)

The most probable number method (EMS) is recommended by many organizations as a standard method in coliform group searching and escherichia coli number determination studies. However, solid media method is preferred this time especially when counting studies are performed for isolation purposes. The solid media medium commonly used for this purpose is Violet Bile Red (VRB) Agar. Methods of smearing, pouring and double layer casting are applied in the counting studies performed on this medium. Another option for VRB Agar solid media is to use the Petrifilm VRB method. In this case, it is preferred to use the VRB Lactose Agar medium.

Agar is used as a thickener in microbiology tests and electrochemistry laboratories and even in food industry in making soup, jelly foods and ice cream.

In the medium composition other cold-water soluble compounds are used instead of agar as the hardening agent. These compounds are commercially available, dried and coated with plastic film.

Another method of determining the number of escherichia coli in solid media utilizes Tryptic Soy Agar (TSA) medium. With this method, more accurate results are obtained in the counting of damaged escherichia coli cells.

There are other solid media used for coliform bacteria isolation. Total bacterial counts are generally performed for hygiene control purposes. By total bacteria, total mesophilic aerobic bacteria are meant. Plate count agar, especially on a solid medium standard smearing or pouring method after planting and incubation colonies are counted bacteria. Plate Count Agar medium is used for bacterial analysis in accordance with ISO 4833 and other international standards.

In advanced laboratories, microbiological analyzes are carried out for the determination of E. coli (in solid media).

  • Food chain microbiology - Horizontal method for enumeration of microorganisms - Part 4833: Colony count at 1 grade using cast plate technique
  • Food chain microbiology - Horizontal method for enumeration of microorganisms - Part 4833: Colon count at 2 grade by spreading plate technique