Identification of nonlipophilic corynebacteria isolated from dairy cows with mastitis

Nonlipophilic corynebacteria associated with clinical and subclinical masti tis in daily cows were found to belong to four species: Corynebacterium amy colatum, Colynebacterium ulcerans, Corynebacterium pseudotuberculosis, and Corynebacterium minutissimum. These species may easily be confused. However , clear-cut difference between C. ulcerans and C. pseudotuberculosis were f ound in their acid production from maltotriose and ethylene glycol, suscept ibility to vibriostatic agent O129, and alkaline phosphatase. Absence of gr owth at 20 degrees C and lack of alpha-glucosidase and 4MU-alpha-o-glycosid e hydrolysis activity differentiated C. amycolatum from C. pseudotuberculos is and C. ulcerans. The mastitis C. pseudotuberculosis strains differed fro m the biovar equi and ovis reference strains and from caprine field strains in their colony morphologies and in their reduced inhibitory activity on s taphylococcal beta-hemolysin, C. amycolatam was the most frequently isolate d nonlipophilic corynebacterium.