i<AMILY I. MYCOBACTERIACEAE 



711 



ganism as a member of the genus Mycococcus 

 on the basis of the resting cells and branch- 

 ing rods; it resembles a tetracoccus on the 

 basis of the characteristic cell groupings. 

 It differs from Mycococcus capsulatus in 

 that the capsules form on practically all 

 media. 



Source: Isolated from soil of the Quy- 

 bishev Agricultural Institute. 



Habitat: Infrequently found in soil. 



4. Mycococcus luteus Krassilnikov, 

 1938. (Microbiologia (Russian), 7, Part I, 

 1938, 349.) 



lu'te.us. L. adj. luteus yellow. 



Original description supplemented by 

 material from Krassilnikov (Guide to the 

 Actinomycetes, Izd. Akad. Nauk, U.S.S.R., 

 Moskau, 1941, 217). 



Cells coccoid, ovoid or irregular, 0.5 to 

 0.8 micron in diameter, united somewhat 

 into short rods. After 5 to 7 days there are 

 found enlarged, lemon-shaped, spherical 

 cells up to 1.5 microns in diameter; they are 

 later destroyed and disappear. In old cul- 

 tures there are resting cells with thicker 

 protoplasm; they reproduce like the spores 

 of an actinomycete. In liquid media, some 

 strains form individual short rods, 0.7 by 

 1.0 micron, which branch infrequently. 



Gelatin: No liquefaction by two strains, 

 weak liquefaction by one. 



Colonies: Bright yellow, sometimes 

 golden or brown. No soluble pigment. 



Milk: No coagulation; no peptonization. 



Sucrose is weakly inverted. 



Acid from glucose and fructose; no acid 

 from sucrose. 



Citric and acetic acids are not utilized as 

 sources of carbon. 



No growth on paraffin. 



Source: Isolated from soil. 



Habitat: Infrequently found in soil. 



5. Mycococcus flavus Krassilnikov, 1941. 

 (Guide to the Actinomycetes, Izd. Akad. 

 Nauk, U.S.S.R., Moskau, 1941, 127.) 



fla'vus. L. adj. flavus yellow. 



Morpholog}^ same as that of Mycococcus 

 luteus. 



Gelatin: Rapid liquefaction. 



Colonies: Brownish yellow; no soluble 

 pigment. 



Milk: Coagulation and peptonization. 



Acid from glucose. 



Starch: No hydrolysis. 



Citric and acetic acids are utilized as 

 sources of carbon. 



Source: Isolated from soil of Zabolgia, 

 Russia. 



Habitat: Infrequently found in soil. 



6. Mycococcus citreus Krassilnikov, 

 1938. (Microbiologia (Russian), 7, Part I, 

 1938, 349.) 



cit're.us. L. adj. citreus of the citrus tree; 

 M.L. adj. citreus lemon-yellow. 



Original description supplemented by ma- 

 terial from Krassilnikov (Guide to the Ac- 

 tinomycetes, Izd. Akad. Nauk, U.S.S.R., 

 Moskau, 1941, 127). 



Cells extremely variable in size: in the 

 same culture are found cells from 0.2 mi- 

 cron and smaller up to 1.0 micron in 

 diameter. Cells are frequently round, single 

 or united into short chains of two or three 

 cells. Protoplasm is light and uniform. Rod 

 forms up to 1.5 microns in length are occa- 

 sionally seen in liquid media; branched 

 forms are observed in hanging drop prepa- 

 rations. Resting forms are found in old 

 cultures. 



Gelatin: Rapid liquefaction. 



Colonies: Yellow-green and lemon- 

 colored; smooth; waxy. 



Milk: Peptonization and coagulation. 



Sucrose is inverted. 



Acid from glucose, fructose and sucrose. 



Nitrites produced from nitrates by most 

 strains. 



Starch: Active hj^drolysis. 



No growth on organic acids. 



No growth on paraffin. 



Comment: Ten cultures were isolated, all 

 of which differed from each other in in- 

 tensity of pigment and in certain physio- 

 logical properties. Krassilnikov regards 

 these differences as insufficient to separate 

 them into distinct species or even strains. 

 One culture, isolated in the Institute of 

 Microbiology of the Academy of Sciences 

 under the name Micrococcus, was found to 

 be Mycococcus citreus. 



Source: Isolated from soil. 



Habitat: Found in soil rather frequently. 



