Dorman: salicin agar

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L-salicin To confirm hns phenotype by monitoring of the bgl operon activity. hns- cells are derepressed for bgl operon and consequent production of phospho-beta-glucosidase, an enzyme that cleaves aromatic beta-glucosides such as salicin. hns- colonies are yellow on plates containing a pH indicator such as bromothymol blue (can use phenol red in liquid culture). Colonies which contain H-NS are blue (bgl operon is silenced).

Recipe: 10g Oxoid tryptone, 5g yeast extract agar, 5g NaCl, 15g agar. Add high purity Analar water (BDH) [we make all our media with this] to 1 Litre.

after autoclaving add;

5g salicin 5ml bromothymol blue stock solution (2% (v/v) bromothymol blue, 50% (v/v) ethanol and 0,2M NaOH).