GROWTH REQUIREMENTS AND METABOLISM OF NEISSERIA

Neisseria intracellularis grows in usual media only scantily. In fact, its ina-bility to grow in plain broth or agar is one of its diagnostic features. The first serious attempt to define the nutrient requirements of neisseriae was made by Mueller and Hinton (1941). They showed that Neisseria intracellu-laris and Neisseria gonorrhoeae grow on a relatively simplified medium (as com-pared to previous routine media) containing an acid casein hydrolyzate, meat infusion, starch, and agar. Their results led to the following conclusions: (1) neisseriae can be grown on a medium in which acid hydrolyzate of casein is used in place of the complicated proteins and peptones usually present in diagnostic media; (2) growth factors present in meat infusion are probably nec-essary for the growth; (3) special physical conditions must be established in the medium. Neisseriae do not grow in the same medium if the starch constituent has previously been broken down by acid or enzyme action. Frantz (1942) announced that Neisseria intracellularis grows in a simple synthetic medium containing glutamic acid, cystine, glucose, and mineral salts. Our study of the growth of Neisseria intracellularis was undertaken after the appearance of Mueller and Hinton's publication (1941). The purpose of our work was to test their results, to simplify the medium if possible, and by this means to obtain information concerning the metabolic processes of neisseriae. We propose to restrict our discussion mainly to aspects in which our results diverge from those of the earlier investigators