172 Decompo!<iti(>)i of Cellulose 



Summary. 



From the foregoing account tlie following summary maj' be given: 



1. Examination of Rothamsted soils on different occasions has 

 revealed the presence of an organism capa))le of breaking down cellulose 

 with comparative ease. 



2. This organism presents a number of features of morphological 

 and physiological interest. Morphologically, the organism appears to 

 possess greater affinities with the Spirochaetoideae than with the 

 bacteria and the name Spirochaeta cytofhaga is, therefore, suggested. 



3. While the spirochaet is capable of considerable vegetative growth 

 as a sinuous filamentous cell, it also appears to pass through a number 

 of phases which terminate in the production of a spherical body (sporoid) 

 which differs in a number of respects from the true spores of the bacteria. 

 Germination of the sporoid again gives rise to the filamentous form, 

 which possesses perfect flexibiUty and is feebly motile. The latter does 

 not apparently possess flagella. 



4. Spirochaeln ojtophac/a is essentially aerobic; its optimum tem- 

 perature is in the region of 30°. Both the thread and sporoid stages are 

 killed by exposure to a temperature of 60° for ten minutes. 



5. The nitrogen requirements of the organism may be met by a 

 number of the simpler nitrogen compounds — ammonium salts, nitrates, 

 amides and amino-acids. Peptone is also suitable in concentrations up 

 to 0-025 per cent. Stronger solutions, e.g. 0-25 per cent., lead to marked 

 inhibition of growth. The organism fails to grow on the conventional 

 nutrient gelatine or agar. 



6. Comparative experiments with a number of higher alcohols, 

 sugars and salts of organic acids show that none of these is capable of 

 meeting the carbon requirements of the organism. Cellulose is the only 

 carbon compound with which growth has been secured. 



7. Although none of the monoses, bioses and other carbohydrates 

 tested is able to support growth, many of them exert an inhibitive 

 action on cellulose decomposition if present in other than very low 

 concentrations. This may be correlated with the reducing properties of 

 the carbohydrate. Maltose, for example, has been found to be approxi- 

 mately 70 times more toxic than saccharose. 



8. Of the various by-products of the action of Spirochaeta cytophaga 

 may be mentioned (a) a pigment possessing relations to the carotin 



