The cultivation of brucellae on chemically defined media.

The selection of a chemically defined medium for nutritional or physiological studies depends upon the objectives of the investigator. The four chemically defined media for the cultivation of brucellae that have been reported during the past decade have tended toward one or the other of two objectives. Either multiple amino acid nitrogen source media have been devised and used to establish the essential or optimal growth requirements of selected strains of these organisms, or the objective has been to establish the minimal nutritional requirements of selected strains. Koser, Breslove, and Dorfman (1941) reported the vitamins that are generally accepted as essential or stimulatory in Brucella nutrition. McCullough, Mills, Herbst, Roessler, and Brewer (1947) reported a comprehensive study of the optimal growth conditions for a strain of Brucella suis. The multiple amino acid media devised by these workers (KBD and MMHRB) contained cystine and methionine as organic sources of sulfur. Each medium contained additional inorganic sulfur, since the required magnesium was added in the form of magnesium sulfate and utilized glucose as an added carbon source. McCullough and Dick (1943), in this laboratory, developed a mineral base medium (MD) containing ammonium sulfate as the sole source of nitrogen, sodium thiosulfate as the primary source of sulfur, and glucose as the carbon source. Gerhardt and Wilson (1948) described a medium (GW) in which either DLasparagine, L-glutamic acid, or L-histidine could serve as the nitrogen source. These workers chose glycerol and lactic acid as their major carbon sources and utilized sodium thiosulfate as the major source of sulfur. The composition of each of these four media is tabulated along with that of our formulation (ROS) in table 1. McCullough and Dick (1942a,b) used theKBD medium in studying the growth response of a number of strains of brucellae and reported failure in their efforts to grow C02-requiring1 strains of Brucella abortus on this medium. McCullough et al. (1947) and Gerhardt and Wilson (1948) reported failure in their efforts to grow selected strains of brucellae on the MD single nitrogen source medium. We have found both the MD and the GW single nitrogen source media inadequate for the cultivation of many strains of brucellae from small inocula. In our cystine toxicity studies (Schuhardt, Rode, and Oglesby, 1949) we found both the KBD and the MMHRB media toxic to certain strains of B. abortus and were