60 PRINCIPLES OF SOIL MICROBIOLOGY 



2. Aerobic bacteria requiring combined nitrogen: 



a. Spore producing bacteria. 



b. Non-spore producing bacteria. 



3. Anaerobic bacteria, requiring combined nitrogen. 



For the sake of convenience three other groups of bacteria may be discussed 

 separately, due to their specific physiological activities and importance in 

 certain soil processes; these bacteria belong, according to their morphology and 

 general physiology, to groups 2 and 3, namely : 



4. Cellulose decomposing bacteria. 



5. Urea and uric acid bacteria. 



6. Denitrifying bacteria. 



