L-Arginine Dihydrolase Medium, Modified

L-Arginine Dihydrolase Medium, Modified is recommended for confirmation of Cronobacter sakazakii (Enterobacter sakazakii) from milk and milk products. It can be differentiated on the basis of their decarboxylation activity of L-Arginine. Bromocresol purple is the pH indicator. Bacteria producing arginine dihydrolase enzyme in this medium decarboxylates arginine to putrescine. The production of amine, putrescine elevates the pH of medium which is detected by the indicator, bromocresol purple which forms purple in alkaline condition. Colour change from purple to yellow and then back to purple is positive reaction. Cronobacter sakazakii gives positive L-Arginine dihydrolase activity and changes colour of the medium to purple.