Modified Sutter's arginine dihydrolase medium for Pseudomonas speciation

Sutter's arginine dihydrolase medium has been modified to obtain maximum yields of arginine dihydrolase. Bromothymol blue is the indicator for alkalinity in Sutter's medium. By adding glucose and lowering the pH of the medium, more positive reactions were obtained in 24 hr as well as a sharper color contrast to the base medium which facilitated reading the reactions. The modified Sutter's medium was included in the routine biochemical schema for speciation of pseudomonads isolated from cosmetic products. Of the 706 strains belonging to the 5 species isolated form cosmetic products, only one false negative reaction was obtained with a strain of Pseudomonas putida. The medium was also used for the biochemical characterization of 122 Pseudomonas sp. isolates.