Question

Differentiate between reserve stock culture and working stock culture. Please include media, incubation temperatures, and purpose.

Answer 1

The differences between reserve and working stock culture is summarised below:

Reserve stock culture

working stock culture

Purpose: serves only as a backup in case of contamination of the working stock. Usually a stab tube and inoculated with a single colony by stabbing a needle 1 time to the bottom of the tube. Using a single stab restricts growth and limits nutrient depletion and toxic waste accumulation. it should be refrigerated at 2-8 degree C. Media: grown on non- selective media such as blood agar plates or in a slant media.

Purpose: the stock that we use throughout the identification process as an inoculum source. usually a slant tube inoculated with an isolated colony by making several passes across the agar surface. The stock organism is kept in the refrigerator at 2-8°C (tightly sealed) in case of working culture. It should be subbed from the stock culture every two weeks or at least monthly depending on the frequency of use and stored at 2-8°C. Media: nutrient broths (liquid nutrient medium) or LB medium (Lysogeny Broth) mixed with agar.