Buffer sodium-chloride-peptone 7.0
The nutrient medium has a high concentration of sodium chloride of which amount has an inhibitory effect on most bacteria, but no effect on the growth of staphylococci. Because of this, the medium is convenient to use for separation of staphylococci. In addition, the nutritional quality of the medium differentiates produce lecithinase staphylococci.
Colonies which produce lecithinase form a "rainbow" area, which is visible when the light is incident at an angle.
Yersinia Medium
Nutrient medium intended for generation of the agents of enteric yersiniosis and pseudotuberculosis. The growth of gram-positive and gram-negative microflora is inhibited. Escherichia coli and Shigella become yellow, via the fermentation of glucose. Yersinia turns yellow within the first 24 hours, as they are also fermented glucose. On the second day of incubation Yersinia breaks down urea and their colonies take on a blue color. Other urea positive microorganisms acquire blue color, slippery, indistinct colonies.
Selenite Broth (Leifson)
Selenite liquid nutrient medium for the accumulation of Salmonella. Selenite inhibits the growth of most bacteria but does not inhibit the development of Salmonella. A feature of the environment is the speed of analysis, selective accumulation is performed for 6 hours. A key factor in the work environment is the pH. To maintain acidic pH in the environment added beckons, from which microorganisms form acid.
Violet red bile agar
Selective agar for the detection and counting of coliforms in water and foods. Bile and crystal violet are inhibitors, in particular, staphylococci. Micro-organisms ferment the lactose and form red colonies with purple halo (due to neutral red and crystal violet that are part of the environment). Bacteria that does not ferment lactose remain colorless.
