COMPREHENSIVE KEY 1011 



30. Organisms grow on agar under aerobic conditions only if heavy inocula are used; 



slightly pleomorphic, including branched forms; 'propionic acid is produced fro7n 

 glucose and also from lactic acid; catalase-positive. . . Propionibacterium p. 569 



(P. arabinosum) 

 Not as above 31 



31. Small spindle-shaped cells usuallj^ occurring in long intertwined chains in liquid media; 



microaerophilic; ferments glucose with the production of ethyl alcohol with small 

 amounts of CO2 and acetic acid and possibly lactic and formic acids; acid and gas 



in glucose in 3 to 5 days Zymobacterium p. 577 



Not as above 32 



32. Colonies usually 1 mm or less in diameter, colorless, little or no growth on media de- 



void of carbohydrates; rods frequently arranged in chains, grow in glucose broth, 

 producing a pH much below 6.0; acid produced from lactose by all species except 



L. delbrueckii and L. brevis Lactobacillus p. 5^3 



Not as above 33 



33. Lactose fermented; cells pleomorphic; arranged in palisades and chinese-letter forms; 



frequently bar-shaped, beaded and clubbed Corynebacterium p. 579 



Lactose not fermented 31 



31. Organisms occur singly, in pairs or in short chains; not pleomorphic 



Brevibacteriiim p. 490 

 (See also B. healii) 

 Organisms normally found in palisade or chinese-letter forms, pleomorphic; barred, 



beaded and club-shaped forms common Corynebacterium p. 579 



Note: Criteria for separation of these two genera are inadequate. 



35. Organisms produce a true branching mycelium which later disintegrates into simple 



rods, cocci and rods with remnants of branches Actinomyces p. 7^2 



Organisms do not branch or, if branching occurs, it is limited to bifurcations and 

 branching of isolated rods; no true mycelium formed 36 



36. Endospores produced 37 



No endospores produced 38 



37. Organisms reduce CO2 to CH4 while oxidizing secondary alcohols to ketones and primary 



alcohols to acids Methanobacterium p. 250 



{M. omelianskii) 

 Not as above Clostridium p. 634 



38. Cells motile; gas produced from peptone in the absence of carbohydrates 



Cillobacterium p. 566 

 Note: Glucose and other carbohydrates are fermented by all species; butyric 

 acid is frequently among the byproducts. 

 Cells non-motile 39 



39. Visible gas produced in culture media either in the presence or absence of carbohj'drates 



40 



Note: In the ensuing section of the key, from 40 to 44 inclusive, the statement 

 "acid from" infers "acid" or "acid and gas," since it is not clear whether gas 

 produced in the presence of carbohydrate arises from the fermentation of the 

 sugar or action on the peptone. 



Visible gas in culture media either in the presence or absence of carbohydrates; glucose 

 fermentation not recorded; pathogenic to guinea pigs; rods occur singly, in pairs, 

 in V-formation, in short chains and in clumps. 

 See Eubacterium niosii and Eubacterium guintum 



No visible gas produced in culture media in the presence or absence of carbohydrates 

 45 



40. Acid produced from glucose, lactose and fructose 41 



Acid produced from glucose and fructose but not from lactose 42 



