172 Transformation of Nitrogen 



Chitin is found among the synthesized constituents of the cells 

 of microorganisms, especially fungi, and is constantly added to the 

 store of soil organic matter. It consists of one molecule of glucos- 

 amine and three molecules of acetyl-glucosamine, from which four 

 molecules of water have been removed (C30H50O19N4). 



Ammonia Formation by Microorganisms 



The earlier investigators of bacterial metabolism, like Hoppe- 

 Seyler, Bienstock, and Hauser, found that mixtures and pure cultures 

 of bacteria, like Proteus vulgaris. Bacillus subtilis, Serratia mar- 

 cescens, Clostridium putrificus, and Fseudomonas fluorescens lique- 

 faciens, are capable of breaking down proteins with the formation 

 of various end products, one of which is ammonia. Proteins of both 

 plant and animal origin are decomposed by a number of bacteria, 

 giving a great variety of products. 



Marchal used a solution containing 1.5 per cent nitrogen, in the 

 form of egg albumin made insoluble by means of 0.01 per cent ferric 

 sulfate, which was inoculated with various bacteria; ammonia was 

 determined, after 20 days' incubation at 30°C, by distilling with 

 MgO. 



Strains of B. rnycoides derived from different som-ces varied in 

 their power to produce ammonia from proteins. With one strain, 

 Marchal obtained a transformation of 58 per cent of egg-albumin 

 nitrogen into ammonia, accompanied by a marked change of the 

 reaction of the medium to alkaline. The more dilute the solution 

 of the protein, the greater was the transformation. 



The great majority of soil organisms developing on the plate were 

 found to produce ammonia from proteins. The gelatin-liquefying 

 bacteria are capable of inducing greater protein decomposition with 

 more abundant ammonia formation. Since the members of this 

 group form at times more than 15 per cent of the total number of 

 soil bacteria developing on the plate, they were believed to do the 

 initial work in rendering soluble the protein nitrogen in the soil, so 

 that it might be further decomposed by the same or other soil organ- 

 isms. 



According to Conn, however, the non-spore-forming bacteria are 

 much more active in manured soil than the spore-forming organisms. 

 Bacillus cereus was found to decompose proteins to amino acids, 

 whereas Fs. fluorescens acts largely upon amino acids. In the pres- 

 ence of a mixture of the two organisms, the protein is rapidly changed 



