Page:Bergey's manual of determinative bacteriology.djvu/525

 Short rods which at first hang very closely together usually in pairs, also in fours or longer chains. Later, however, longer chains are regularly formed. The diameter of the cells is about 0.5, the length 1.5 to 2.5, microns, at times as long as 4.5 microns. The rods rotate on their long axis (Lehmann and Neumann state that their culture was non-motile). Gram-positive. Gelatin plates: The colonies within the gelatin are small, spherical bodies that are bright yellow in color. The colonies on the surface are highly convex, bright yellow, tin}' drops which lie in a shallow depression. When examined under low magnification, the colonies beneath the surface appear as pale yellowish to brownish, granular, cir- cular, sharply contoured discs. The colonies on the surface also show a sharp contour for some time; however, they later become somewhat irregular in contour and appear much darker brown by transmitted light. Gelatin stab : An elevated growth is formed at first on the surface. This is a definite Naples-yellow in color. This growth gradu- ally spreads until it almost reaches the glass wall of the test tube. By this time the gela- tin is liquefied in a shallow layer. There is little development along the stab. The lique- faction proceeds slowly. Agar slant: There is an abundant, rather rapid growth that is of a definite light yellow color as on gelatin. (Lemon-yellow, Leh- mann and Neumann.) Bouillon broth: The broth becomes some- what lighter in color with little turbidity at first; then flecks form and settle, appearing as a j'ellowish white sediment. Potato: The yellow growth is abundant, becoming thickened and glistening. The color becomes somewhat greenish but not enough to call it sulfur-yellow. Indole is not produced (Lehmann and Neumann). Hydrogen sulfide is actively produced (Lehmann and Neumann). No gas produced from glucose (Lehmann and Neumann). Milk is coagulated (Lehmann and Neu- mann). Optimum temperature, about 25° C. Aerobic. The specific epithet helvolits is suggested because of its pale yellow chromogenesis on agar plates. Comments: It will be seen that the de- scription by Zimmermann differs in several important respects from that given in the 6th edition of the Manual, 1948, 395; the latter was taken largely from Jensen (Proc. Linn. Soc. New So. Wales, 59, 1934, 37). The morphology of the Zimmermann organism both as described by him and also by Leh- mann and Neumann is that of a simple, unbranching rod. There is no suggestion of a pleomorphic morphology, snapping divi- sion or branching. The description given by Jensen is indicative of a different species, and when Lochhead compared a culture of Jensen's organism with cultures of related organisms, he found it (personal communi- cation, 1954) to be identical with cultures of Bacterium globiforme Conn, the organism selected as the type species of the genus Arthrobacter Conn and Dimmick. Zimmer- mann 's organism clearly was a Brevihac- terium as defined here, not a Corynebacter- ium as defined by Lehmann and Neumann (Bakt. Diag., 1 Aufl., 2, 1896, 380). Brevi- hacterium represents a segregation of species placed by Lehmann and Neumann in Bac- terium. Source : Isolated from Chemnitz tap water (Zimmermann) ; also found as a dust con- taminant in Wiirzburg (Lehmann and Neu- mann). Habitat: Presumably widely distributed in nature. Genus II. Kurthia Trevisan, 1885. (Trevisan, Atti della Accad. Fisio- Medico- Statistica in Milano, Ser. 4, S, 1885, 92; Zopfius Wenner and Rettger, Jour. Bact., 4, 1919, 334.) Kurth'i.a. M.L. fem.n. Ki<r/Am named for H. Kurth, the German bacteriologist who de- scribed the type species. Long rods with somewhat rounded ends. In liquid media the cells are aligned in evenly