I used this broth according to manufacture recommendation in preparing the media
http://www.titanmedia.in/images/upload/td/TM%201140_ARGININEDIHYDROLASEBROTHTM-1140.pdf
Are you maintain the +ve control for the same ?
which culture are you use ?
An inoculum from a pure culture is transferred aseptically to a sterile tube of arginine dihydrolase broth. The inoculated tube is incubated at 35-37 C for 24 hours and the preliminary results are determined. The microbe must first use the glucose present to cause the pH to drop. This is indicated by a change from purple to yellow. Once the medium has been acidified, the enzyme arginine dihydrolase is activated. The culture is incubated an additional 24 hours at 35-37 C to allow the microbe to now use the arginine. The final results are then obtained by observing the tube at 48 hours. Change back to purple from yellow indicates a positive test for arginine dihydrolase. Failure to turn yellow at 24 hours or to revert back to purple at 48 hours indicates a negative result.
So, for +ve results you should use pure culture of arginine utilizing Bacteria. Salmonella Typhi, Salmonella Typhimurium will give +ve result.
i used pure culture of Salmonella Typhimurium and didnt give any color change after 24h and 48h
Reperform the test, after autoclave kindly check pH which should be around 6.0.
and do this test with another +ve microorganism, maintain pH strictly.
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