194 



PRINCIPLES OF SOIL MICROBIOLOGY 



succeeded in isolating from the intestine of man an obligate anaerobic 

 organism, Bac. cellulosae dissolvens, capable of decomposing cellulose 

 very vigorously, especially in mixed culture. The organism was 2.5 

 to 12.5^ long, and did not form any flagella; the spores were 2.5 

 by 2n in size. It was cultivated upon a medium containing fecal mat- 

 ter as a source of nitrogen. The spores were killed only on boiling for 

 45 to 50 minutes. The organism decomposed cellulose at 38° to 51°C, 

 without any distinct optimum. When the oxygen tension of the atmos- 

 phere was above 12 mm. mercury, no growth took place. The organism 

 clung to the paper, so that the contaminating forms could be removed by 

 washing the paper with sterile salt solution. Sixty per cent of the cel- 



TABLE 14 

 Summary of characteristics of two anaerobic cellulose decomposing bacteria 



Size of rods 



Size of spore 



Flagella 



Nutrient broth with or with- 

 out glucose 



Nutrient agar 



Potato slant 



Milk 



Carbohydrates decomposed 



BACILLUS CELLULOSAE 



DISSOLVENS— 



KHOUVINE 



2.0x2 to 12 ix 

 2.0x2.5^ 



Absent 



No growth 



No growth 



No growth 

 No growth 

 Only cellulose 



CLOSTRIDIUM THEPMOCELLU 

 V, P AND P 



5.0x0.4 M 

 0.9x0.6^ 

 Peritrichous 



Ring, pellicle and sediment; 



acid and gas with glucose 

 Small surface and subsurface 



colonies on starch agar 

 Yellow growth, potato browned 

 Acid curd in three days 

 Hemicellulose, starch, various 



hexoses and pentoses 



lulose decomposed was accounted for by the carbon dioxide, hydrogen, 

 ethyl alcohol, acetic and butyric acids, and a brown pigment. The 

 presence of other bacteria greatly stimulated the power of this organism 

 to decompose cellulose. The organism was found to be also abundantly 

 distributed in the soil, occurring in all soil types, under various 

 conditions. 



The results of other investigators 8 also point to the anaerobic nature 

 of cellulose decomposing bacteria in the digestive tract of horses. 

 Under anaerobic conditions, cellulose decomposition is carried out 

 entirely by bacteria; the nature of the processes involved being different 



8 Hosslin, A., and Lesser, liber die Zersetzung der Zellulose durch den Inhalt 

 des Coecums des Pferdes. Ztschr. Biol. 54: 47. 1910. 



