Page:Bergey's manual of determinative bacteriology.djvu/731

 month's cultivation, dissociated into a stable mycobacterial culture which was dis- tinct from the original culture in structure and size of cells. After one day's growth, cells were rod-shaped, 0.6 to 0.7 by 2.0 to 3.5 microns; they curved slightly and had irregular contours; on salt agar and es- pecially in liquid media and peptone broth, cells up to 5 microns were found, often ex- hibiting branching. Krassilnikov regarded the history of the development of this strain to be the same as that of typical my- cobacteria, since these rods became shorter and changed into a coccus-like stage. Rest- ing forms then developed, completing the cycle. Cultural and physiological properties were not different from those of the original culture. In view of the morphological char- acteristics and the cycle of development, this culture was referred to as Mijcobac- terium albns Krassilnikov (1916) under the name Micrococcus candicans; this organism formed rod-shaped cells with side branches under certain conditions (Lohnis and Smith, Jour. Agr. Res., 6, 1916, 675-702). Spassky (Zent. f. Bakt., I Abt., Orig., 128, 1933, 245) described a streptococcus which gave rise to a mycobacterial strain in the process of dissociation. Krassilnikov sug- gests that the original culture of both these organisms belonged to the genus Myco- coccus. Source: Isolated from soil. Habitat: Infrequently found in soil. lb. IMycococcus albus subsp. lactis Krassil- nikov, 1941. (Guide to the Actinomycetes, Izd. Akad. Nauk, U.S.S.R., Moskau, 1941, 125.) lac'tis. L. noun lac milk; L. gen. noun lactis of milk. Morphological and cultural characteris- tics are the same as those of Mycococcus albidus. Gelatin: No liquefaction (two months). Milk: Acid; rapid coagulation. No pep- tonization within 30 days. Coagulation ap- parently takes place through the production of acid in a manner similar to that of the lactic acid bacteria. Sucrose is inverted. Acid from glucose and lactose; slight acid from sucrose. Starch weakly hydrolyzed. Comment : Krassilnikov regards as closely related to this species a culture described by Lieberman (1935) under the name Strepto- coccus lactis. Source: Isolated from soil. Habitat: Infrequently found in soil. 2. Mycococcus ruber Krassilnikov, 1938. (Microbiologia (Russian), 7, Part I, 1938, 349.) ru'ber. L. adj. ruber red. Original description supplemented by material from Krassilnikov (Guide to the Actinomycetes, Izd. Akad. Nauk, U.S.S.R., Moskau, 1941, 125). Cells spherical, irregularly rounded, slightly compressed, somewhat angular, 0.5 to 0.9 micron in diameter. In liquid cultures there are occasionally found short rods, 0.7 by 0.8 to 1.0 micron, with branches; en- larged cells of different shapes are also found. In old cultures are found resting cells which germinate in a mannei similar to that of the spores of actinomycetes. Not acid-fast. Gram-positive. Gelatin: No liquefaction. Colonies: Dough-like consistency; smooth; weak shine. Colonies dark brown, rose, red-orange or, frequently, orange. A culture may show different pigmentation on different media. Pigment not soluble. Milk: No coagulation or peptonization. Sucrose not inverted. Sucrose and organic acids (acetic and citric) are utilized as sources of carbon. Starch : No hydrolysis or weak hydrolysis with a clear zone only under the colonies. Nitrites not produced from nitrates. Nitrates and ammonium salts are readily utilized as sources of nitrogen. Some strains produce good growth on paraffin. Some strains grow well in high concentra- tions of salts, such as 10 per cent NaCl and 10 to 20 per cent sodium sulfate. Resistant to desiccation. Comments: Krassilnikov isolated several strains which could be distinguished on the basis of shades of pigmentation of the colony and by the size of the cells. Strains Nos. 3 and 5 were blood-red on all media; cells 0.6 to 0.9 micron, frequently 1.0 micron, in diameter. Strain No. 45 was rose-red, red or