CLASSIFICATION OF THE BACTERIA 27 



Key to Genera of Bacteria op Agricultural and Indus- 

 trial Significance 



A. Typically never filamentous nor producing a 

 mycelium. 

 B. Cells spherical. 



C. Cells occurring typically in chains. 

 D. Cells forming gelatinous masses in su- 

 gar media, saprophytic Leuconostoc. 



DD. Parasitic. Cells not forming zoo- 



giloeal masses Streptococcus. 



. CC. Cells not in chains. 

 D. Cells typically in pairs. 



E. Cells Gram-negative. Uusually coiTee- 



bean-shaped Neisseria. 



EE. Cells Gram-positive. Usually lan- 

 ceolate Diplococcus. 



DD. Cells hot in pairs. 



E. Typically parasitic. Cells in irregu- 

 lar groups Staphylococcus. 



EE. Typically saprophytic. 



F. Cells arranged in regular packets. Sarcina. 

 FF. Cells not arranged in packets, not 

 regularly grouped. 



G. Piginent usually yellow Micrococcus. 



GG. Pigment red Rhodococcus. 



BB. Cells elongate, not spherical. 

 C. Rods not spiral or curved. 



D. Cells acid fast Mycobacterium. 



DD. Cells not acid fast. 

 E. Endospores present. 



F. Aerobic Bacillus. 



FF. Anaerobic Clostridium. 



EE. Endospores absent. 



F. Not growing on ordinary organic 

 media, oxidizing ammonia or ni- 

 trites. 



G. Oxidizing ammonia Nitrosomonas. 



GG. Oxidizing nitrous acid Nitroba^ter. 



FF. Not securing growth energy by ox- 

 idation of ammonia or nitrites. 

 G- Oxidizing carbon compounds aero- 

 bically, saprophytic. 



H. Oxidizing alcohol to acetic acid. Acetobacter. 

 HH. Oxidizing carbohvdrates. 

 Fixing atmospheric nitrogen. 



I. Cells relatively large. Free 



living' soil bacteria Azotobacter. 



II. Cells smaller. Symbiotic in 



roots of leguminous plants. Rhizohium. 



