o24 BACTERIOLOGICAL CHEMISTRY 



bacillus being " swamped out." These two organisms 

 are very widely distributed in soil and mud. 



It is possible that Gl. methanigenes does not itself 

 attack cellulose, but that it forms methane by the 

 reduction of products formed by CI. fossicularum from 

 cellulose. 



It is claimed that in most herbivorous animals 75 per 

 cent, of the cellulose which they digest is hydrolysed by 

 bacteria and not by the digestive fluids. 



2. Anaerobic at High Temperature. — A number of 

 thermophilic organisms decomposing cellulose have been 

 isolated from soil and rotting plant residues. MacFadyen, 

 in 1894, isolated several such organisms from rotting 

 straw and showed that they grew at 60° C. and produced 

 acetic and butyric acids together with methane and 

 carbon dioxide. They were not pure cultures. CI. 

 thermocellum, isolated in America, decomposes cellulose 

 at 62° to 66° C. with formation of acetic acid and ethyl 

 alcohol. CI. dissolvens resembles Omelianski's CI. fossicu- 

 larum morphologically, but grows up to a temperature of 

 65° C. Cellulose, the only carbohydrate which it will 

 attack, is broken down to acetic acid, lactic acid, butyric 

 acid, alcohol, carbon dioxide and hydrogen. CI. cellulo- 

 lyticum (which may be identical with B. thermocellulyticus) 

 breaks cellulose down with conversion of 64 per cent, of 

 it to volatile acids of which 80 per cent, is formic acid 

 and about 16 per cent, acetic acid, the remainder being 

 propionic acid. 



3. Aerobic Fermentation at 20° to 37° C. — A number of 

 aerobic organisms decomposing cellulose are known, but 

 usually they are in mixed cultures and are often symbiotic. 

 Neither their bacteriology nor chemistry has yet been 

 worked out satisfactorily. They produce acetic, butyric 

 and lactic acids, which are further broken down by other 

 organisms to water and carbon dioxide. 



CytopJutga liutcliinsoni converts a])out two-thirds of 

 the carbon of the cellulose attacked into carbon dioxide. 



