KEY TO ORDERS AND SUBORDERS 67 



Sub-Order I. Eubacteriineae Breed, Murray and Kitchens. 

 (Jour. Bact., 47, 1944, 421.) 



These are, as the name Eubacteriinae implies, the true bacteria in the narrower 

 sense of the word. The cells are rigid and free. Branching occurs only under ab- 

 normal conditions of life. They are not attached by holdfasts nor stalks. They 

 form no sheaths. One-third of the species form pigments, but these have no photo- 

 synthetic properties. Endospores occur in one familj^ {Bacillaceae), rarely in others. 



Key to the Families of the Sub-Order Eubacteriineae. 



I. Xo endospores (except Sporosarcina) . 



A. Can develop on inorganic media. Autotrophic and facultative autotrophic. 



Famil}' I. Nitrobacteriaceae, p. 69. 



B. Cannot develop on inorganic media (exceptions, see Family XII. Bacteriaceae). 

 Heterotrophic. 



1. Polar flagellate, straight, curved or spiral rods. Gram-negative. (Some 

 species with a single flagellum will be found under Family IV. Rhizobiaceae, 

 Family V. Micrococcaceae and Family VIII. Corynebacteriaceae) . 



Family II. Pseudomonadaceae , p. 82. 



2. Large, oval, pleomorphic cells sometimes almost yeast-like in appearance. 

 Free living in soil. Fix free nitrogen. Poritrichous flagellation. 



Family III. Azoiobacteriaceae, p. 219. 



3. Peritrichous or non-motile rods, and cocci. 



a. Heterotrophic rods which may not require organic nitrogen for growth. 

 Usually motile with one to six or more flagella. Usually form nodules 

 or tubercles on roots of plants, or show violet chromogenesis. 

 Family IV. Rhizobiaceae, p. 223. 

 aa. Heterotrophic rods or cocci which utilize organic nitrogen and usu- 

 ally carbohydrates. 



b. Spherical cells in masses, tetrads, and packets. A few species are 

 motile with one or two flagella. 

 c. Gram-positive to Gram-negative cocci. Not obligate 

 parasites. 



Family V. Micrococcaceae, p. 235. 

 cc. Gram-negative, and sometimes anaerobic cocci. Obligate 

 parasites. 



Family VI. Neisseriaceae, p. 295. 

 bb. Spherical cells which grow in pairs and chains; and rods. 



c. Gram-positive cocci and rods. Non-motile (some species of 

 Streptococcaceae or Corynebacteriaceae may show motility), 

 d. Microaerophilic to anaerobic cocci and rods. Frequently 

 in chains. Active in the fermentation of sugars. Never 

 reduce nitrates. 



Family VII. Lactobacteriaceae , p. 305. 

 dd. Usually aerobic, but sometimes anaerobic rods. Less 

 active in the fermentation of sugars. May or may not 

 reduce nitrates. 



Family VIII. Corynebacteriaceae , p. 381. 



