FAMILY XII. CORYNEBACTERIACEAE 



611 



showing pronounced cytomorphosis. The 

 cells are curved or swollen and often possess 

 rudimentary branches as well as deeply 

 staining granules. Older cultures contain 

 many small cocci, 0.5 to 0.6 micron in di- 

 ameter, which arise from the fragmentation 

 of the longer rods. After two to three days, 

 many spherical cells (cystites), up to 3.0 

 microns in diameter, occur from which one 

 to four rod forms may arise by germination. 

 Non-motile. Gram-negative with Gram- 

 positive granules; coccoid forms are Gram- 

 negative to Gram-positive. 



Gelatin stab: Saccate liquefaction (4 to 

 5 daj^s), becoming stratiform; cream-colored 

 surface growth and sediment; liquid finely 

 flocculent. 



Agar colonies : Punctiform, grayish cream- 

 colored, flat, translucent. 



Agar slant: Growth scant, filiform, fiat, 

 grayish cream-colored, translucent. 



Soil extract agar slant: Growth moderate, 

 filiform, whitish, opaque, dull, soft. 



Asparagine agar slant: Growth scant, 

 filiform, thin, fiat, colorless. 



Broth: Slightly turbid; no surface growth; 

 slight sediment; faintly acid. 



Potato: Growth abundant, pale brown, 

 glistening, membranous. 



Milk: Soft coagulation (10 to 12 days) 

 followed by slow digestion; no change in 

 reaction. 



Indole not produced. 



Hydrogen sulfide not produced. 



Slight or no acid produced in sugar broth; 

 no gas produced. 



Acetylmethylcarbinol not produced. 



Starch weakly hj'drolyzed. 



Nitrites produced from nitrates. 



Urease not produced. 



Unable to utilize nitrates or ammonium 

 salts as nitrogen source, or citrates as sole 

 carbon source. 



Catalase-negative. 



Aerobic. 



Optimum temperature, between 30° and 

 32° C.; poor growth at 20° and 37° C.; no 

 growth at 10° C. 



Source: Isolated from Australian soils. 



Habitat: Soil. 



8. Arthrobacter citreus Sacks, 1954. 

 (Jour. Bact., 67, 1954, 342.) 



cit're.us. L. adj. citreus pertaining to the 

 citrus tree; M.L. adj. citreus lemon-col- 

 ored. 



Rods, usually 0.8 by 2.0 to 5.0 microns, 

 which occur in V-shaped pairs as a result of 

 snapping division. The individual cells are 

 irregular, curved or swollen and show a 

 slight tendency to branch. The rods rapidly 

 undergo fragmentation, usually within 24 

 hours, to give rise to forms indistinguish- 

 able from true cocci; these forms measure 

 0.7 micron in diameter. Feebly motile. 

 Gram-variable. 



Gelatin stab: Slow, crateriform liquefac- 

 tion, becoming stratiform; moderate surface 

 growth; considerable yellowish sediment; 

 liquid turbid. 



Agar colonies: Circular, entire, low con- 

 vex, lemon-yellow, glistening. 



Agar slant: Growth abundant, filiform, 

 fiat, lemon-yellow, smooth, glistening, soft. 



Soil extract agar slant: Growth moderate, 

 filiform, fiat, yellow, glistening, soft; sur- 

 face has a fine "ground glass" appearance. 



Asparagine agar: Growth scant, filiform, 

 thin, colorless. 



Broth : Slightly turbid ; no surface growth ; 

 slight sediment; reaction unchanged. 



Potato: Growth scant, slightly raised, 

 dull, yellow. 



Milk: No change. 



Indole not produced. 



Hydrogen sulfide not produced. 



Little or no acid produced from carbo- 

 hydrates. 



Acetylmethylcarbinol not produced. 



Starch not hydrolyzed. 



Nitrites produced from nitrates. 



Urease not produced. 



Unable to utilize nitrates or ammonium 

 salts as nitrogen source, or citrates as sole 

 carbon source. 



Catalase-positive. 



Aerobic. 



Optimum temperature, between 25° and 

 30° C.; grows well at 20° to 32° C.; fair 

 growth at 10° but little or none at 37° C. 



Source: Isolated from chicken feces. 



Habitat: Soil. 



9. Arthrobacter terrcgens Lochhead 

 and Burton, 1953. (Can. Jour. Botany, SI, 

 1953, 7.) 



