Hetorotropliic Bacteria 75 



cellulose in niuuuie, and the denitrifying forms which decompose 

 cellulose only in the presence of nitrates. 



Omeliansk)' found that the gases liberated in the decomposition 

 of cellulose by anaerobic bacteria contained either hydrogen or 

 methane. On further study, he observed that these two gases seemed 

 to be produced by two different organisms: when the inoculum was 

 added without preliminary heating, methane was formed; when the 

 inoculum was heated for 15 minutes at 75 °C, conditions favored the 

 de\'elopment of bacteria which formed hydrogen. The spore of the 

 methane organism germinated earlier than that of the hydrogen 

 form. When the cultin-e was transferred, the former organism pre- 

 dominated and the latter could finally be eliminated. By heating the 

 inoculum of a young culture, the vegetative cells produced from the 

 spores of the methane form, which had already germinated, were 

 killed, whereas the ungerminated spores of the hydrogen form sur- 

 vived and proceeded to develop. By heating the culture several 

 times, at an early stage of development, the hydrogen-producing 

 type could be obtained free from the methane-producing form. 



Kellerman and associates could not confirm the results of Omelian- 

 sky. They isolated from Omeliansky's cultures an aerobic cellulose- 

 decomposing organism and suggested that the cellulose was decom- 

 posed by aerobic bacteria; the anaerobic organisms accompanying 

 the aerobic bacteria were able to form gas from the products of cellu- 

 lose decomposition. This interpretation has not been universally 

 accepted, howev er. 



Khouvine isolated from the intestine of man an obligate anaerobic 

 organism, B. cclhilosae dissolvens, capable of decomposing cellulose 

 vigorously, especially in mixed culture. The vegetative cells were 

 2.5-12.5 iJL long and produced no Hagella; the spores were 2.5 by 

 2 IX. The organism was cultivated upon a medium containing fecal 

 matter as a source of nitrogen. The spores were killed only on boil- 

 ing for 45-50 minutes. Cellulose was decomposed at a range of 38- 

 51°C. 



Werner isolated from the intestinal tract of the larvae of Protosea 

 cuprea an anaerobic organism, B. ceUulosam fermentans, capable of 

 attacking cellulose but no other carbohydrates. The anaerobic nature 

 of the cellulose-decomposing bacteria in the digestive tract of horses, 

 cattle, termites, and insect larvae was fully confirmed. Under an- 

 aerobic conditions, cellulose decomposition is canied out entirely 

 by bacteria. The mechanism of cellulose decomposition, especially 

 in relation to the nutrition of herbivorous animals, has been studied 



