282 ORDER IV. EUBACTERIALES 



cc. Ferment glucose anaerobically, frequently producing visible gas 

 (CO2 + H2) from glucose and sometimes lactose. Reduce nitrates 

 (rare exceptions). Frequently found in the alimentary, respiratory 

 and urinary tracts of vertebrates, others are free-living, while still 

 others are plant pathogens. 



Famil}^ IV. Enterobacteriaceae, p. 332. 

 bb. Usuallj^ small, motile or non-motile rods. Obligate animal parasites 

 which usually require body fluids for growth. Man}' fail to grow on 

 ordinar}^ media. The majority do not ferment glucose anaerobically. 

 Family V. Brucellaceae , p. 394. 

 B. Anaerobic to microaerophilic, rod-shaped organisms which sometimes show branch- 

 ing. 



Family VI. Bacteroidaceae, p. 423. 

 II. Cells spherical to rod-shaped. Usually Gram-positive, though some cocci and anaerobic 

 spore-forming rods lose the Gram stain readil3^ 



A. Cells do not form endospores. 



1. Cells spherical, occurring in masses, tetrads or packets of eight cells. 



a. Spherical cells. Gram-positive. Aerobic or anaerobic. 



Family VII. Micrococcaceae, p. 454. 

 aa. Cells spherical. Gram-negative. Aerobic or anaerobic. Frequently occur 

 in pairs. 



Family VIII. Neisseriaceae, p. 480. 



2. Cells either spherical, occurring in chains, or rod-shaped. Gram-positive, but 

 cells may lose the Gram stain readily in old cultures. 



a. Cells rod-shaped, no pleomorphism or branching of cells. Rarely or never 

 ferment glucose anaerobically. 



Family IX. Brevibacteriaceae, p. 490. 

 aa. Not as above. 



b. Gram-positive cocci and rods which frequentl}' form chains of cells. 

 Cells ferment sugars anaerobically with the production of lactic, acetic, 

 propionic, butyric, etc. acids. Microaerophilic to anaerobic, 

 c. Homo- and hetero-fermentative cocci and rods whose chief product 

 in fermentation is lactic acid. Do not reduce nitrates. 

 Family X. LactobaciUaceae, p. 505. 

 cc. Rod-shaped bacteria whose distinctive product in fermentation is 

 propionic acid, butyric acid or ethanol. All produce CO2 . 



Family XI. Propionibacteriaceae, p. 569. 

 bb. Cells generally rod-shaped but wedge and club forms are common. The 

 cells are usually found in angular or picket formations due to snapping 

 division. Old cells are frequently Gram-negative. Not active in the an- 

 aerobic fermentation of sugars. May or may not reduce nitrates. 

 Family XII. Corynebacieriaceae, p. 578. 



B. Rod-shaped cells that produce endospores. Aerobic and anaerobic. Some anaerobic 

 species lose the Gram stain readily. 



Family XIII. Bacillaceae, p. 613. 



