Egg yolk emulsion

Egg yolk emulsion is a mixture of egg yolk, typically from chicken eggs, and an aqueous solution, usually saline or phosphate-buffered saline (PBS). It is commonly used in microbiology and related fields as a growth supplement for bacteria and other microorganisms. The emulsion provides a complex mixture of nutrients, including lipids, amino acids, and vitamins, that support the growth of a wide range of microorganisms. Egg yolk emulsion can be added to a variety of microbial culture media to improve the growth of fastidious bacteria that require specific nutrients or additional growth factors. It is particularly useful for the cultivation of bacteria that need cholesterol for growth, such as Mycobacterium species and some of the anaerobic bacteria.

Egg yolk emulsion is commonly used for the cultivation of Mycobacterium tuberculosis and other Mycobacterium species, as well as for the growth of anaerobic bacteria. In addition, egg yolk emulsion can be used as a component of enrichment broths to improve the recovery of pathogens from food samples. Egg yolk emulsion can also be used as an ingredient in selective media formulations, such as egg yolk-polymyxin agar, used for the selective isolation of anaerobic bacteria from various samples.

Replaces: 1.03784.0007

Sterility test: sterile
Typical composition: Sterile egg-yolk 500 ml; NaCl 4.25 g; distilles water to give a final volume of 1000 ml.
Growth promotion test in accordance with ISO 11133.
Egg-yolk Emulsion tested in Mannitol-Egg-yolk-Polymyxine -Agar (=MYP-agar) Art. 1.05267.
Growth
- Bacillus cereus ATCC 11778 (WDCM 00001):
good growth
- Bacillus subtilis ATCC 6633 (WDCM 00003): no limit
- Escherichia coli ATCC 8739 (WDCM 00012): no growth
- Escherichia coli ATCC 25922 (WDCM 00013): no growth
Colony colour
- Bacillus cereus ATCC 11778 (WDCM 00001):
pink
- Bacillus subtilis ATCC 6633 (WDCM 00003): yellow
Precipitate
- Bacillus subtilis ATCC 6633 (WDCM 00003):
-
- Bacillus cereus ATCC 11778 (WDCM 00001): +
Incubation: 48 hrs. 30 °C; B.cereus 24-48 hrs. 30 °C.