CLASSIFICATION OF THE BACTERIA 27 



KEY TO GENERA OF BACTERIA OF 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- 



gloeal masses Streptococcus. 



CC. Cells not in chains. 

 D. Cells typically in pairs. 

 E. Cells Gram-negative. Uusually coffee- 

 bean-shaped Neisseria. 



EE. Cells Gram-positive. Usually lan- 

 ceolate Diplococcus. 



DD. Cells not 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. Pigment 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 a<-id 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 Xitrosomonas. 



GG. Oxidizing nitrous acid Kitrobacter. 



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. Oxidbing carbohvdrates. 

 Fixing atmospheric nitrogen. 



I. Cells relatively large. Free 



living soil bacteria. Azotobacter. 



II. Cells smaller. Symbiotic in 



roots of leguminous plants. Rhizobium. 



