you inoculate a simmons citrate agar slant tube with an unkn

you inoculate a simmons citrate agar slant tube with an unknown bacterium and incubate it at 37 C. The next day the color of the slant is green. Do you expect to see bacterial growth? If yes or no, give explanation

Solution

If the colour of the Simmons citrate agar slant is green, then the result is that there is no bacterial growth. Simmons citrate agar tests the microorganism’s ability to use citrate as energy source. When the bacteria grow on this medium, they metabolize citrate, the ammonium salts are broken down to ammonia. Ammonia increases the alkalinity of the medium. This increase in pH turns the bromothymol blue indicator in the medium to change colour from green to blue. Thus obtaining a green slant is indicative of a negative result and there would be no bacterial growth.