Malonate Broth, Ewing Modified

Malonate Broth, Ewing Modified is used for differentiation of members of Enterobacteriaceae on the basis of malonate utilization. An organism that can simultaneously utilize sodium malonate as its carbon source and ammonium sulfate as its nitrogen source produces alkalinity due to the formation of sodium hydroxide. The alkali changes the color of the bromothymol blue indicator in the medium to light blue and finally to prussian blue. The color of the medium remains unchanged in the presence of an organism that cannot utilize these substances.Enterobacter aerogenes, Klebsiella pneumoniae, Salmonella Arizonae utilize malnoate, whereas Escherichia coli, Salmonella Typhimurium do not utilize malonate.