SOME METABOLIC ACTIVITIES OF VIBRIO FETUS OF BOVINE ORIGIN

Little is known concerning the basic nutritional requirements of Vibrio fetus, an organism now recognized to be an important economic cause of sterility in cattle. Attempts to grow the organism in synthetic media have failed, although it will grow in a variety of rather complex media. In an effort to elucidate the nutritional requirements, a study of the oxidative metabolism employing the Warburg respirometer was undertaken. The results are reported here. MATERIALS AND METHODS Cultures. Two cultures of V. fetus which were isolated from aborted bovine fetuses were used; a laboratory strain which had been maintained in thiol medium (Difco) for seven years, and a recently isolated strain. The organisms were catalase positive, reduced nitrates, did not pro-duce hydrogen sulfide, and grew optimally in an atmosphere of 5 per cent oxygen, 10 per cent carbon dioxide and 85 per cent nitrogen (Kiggins and Plastridge, 1956). Preparation of cellular suspensions. Cells for the manometric studies were prepared by inocu-lating the surface of thiol agar (thiol medium with 2.5 per cent added agar) in Kolle flasks with a 48-hr-old thiol culture and incubating the flasks at 37 C in 5 per cent oxygen, 10 per cent carbon dioxide and 85 per cent nitrogen for 24 hr. The cells were suspended in 0.2 M Tris buffer, tris-(hydroxvmethyl)aminomethane, pH 7.0, centri-fuged, and resuspended in Tris buffer so that 1 ml contained approximately 1 mg of total nitro-gen. The nitrogen determinations were made on cells suspended in Sorensen's phosphate buffer (pH 7.0). A loopful of the cell suspension wa