MALONATE BROTH EWING MODIFIED

Leifson developed a synthetic liquid medium, which differentiated Aerobacter (now Enterobacter) from Escherichia species based on their ability to utilize malonate where Enterobacter utilizes malonate and Escherichia does not. Ewing et al further modified this medium by the incorporation of yeast extract and dextrose. The medium, therefore, will support the growth of organisms that cannot utilize malonate or ammonium salt. Any spontaneous alkalinization produced by such organisms is buffered by the phosphate system and counteracted by the acid produced by the fermentation of the small amount of dextrose. An alkaline reaction (blue color) is produced in this medium by organisms capable of utilizing malonate and ammonium sulfate.

for di?erentiation of members of Enterobacteriaceae on the basis of malonate utilization