Hi,

Urea solution (4%, w/v) adds to urea media.

I do not know what your primary medium is which you want to enrich. But if you are going after an enzyme, it is only logical that you incorporate the specific substrate or a pseudo one to induce enzyme synthesis. Urease is an inducible enzyme in the majority of organisms, therefore the presence of urea (40% w/v) should be sufficient for the purpose. What I usually do is to keep out every other source of nitrogen, like the peptone suggested in Christenson broth. Urea is a good source of nitrogen. Its hydrolysis is supposed to generate NH3 and CO2. Since most organisms will not use CO2 as sole source of carbon and energy, the supplementation of the medium with glucose becomes necessary. So, mineral salt medium + urea as nitrogen sole nitrogen source should select for urease-producing microorganisms.

Hi Yakubu,

Basically, when we want to isolate microorganism through enzyme screening, we use selective media containing the substrate of needed enzyme (in your case urease so you should use screening media for urease which contain urea as substrate).

The commercially available media for urease producing microorganisms is Urea Agar Base (Christensen's Urea Agar, Christensen's Agar Base). You can also prepare it. As said by Maurice, keep in mind that urea is used principally as source of nitrogen, so the presence of other sources of nitrogen may give you misleading results.

Good Luck !

Make urea the sole Nitrogen source