INTRODUCTION 



In the course of studies on the production of chemicals from 

 agricultural wastes by the action of microorganisms it seemed 

 advisable to obtain a comprehensive view of the chemicals 

 which have been reported as produced by the action of bacteria, 

 yeasts, and molds on various substrates. A survey was made 

 with reference to non-nitrogenous compounds since such com- 

 pounds furnish the important sources of energy for the 

 organisms and for the zymotechnical production of chemicals 

 on a large scale. This study was further limited to those 

 instances in which a named organism acted on a named sub- 

 strate to produce a named compound. 



To cover the literature completely even with the above 

 limitations would involve so much material as to become un- 

 wieldy. The purpose of this survey is to cite references involving 

 a variety of organisms, substrates, products, and authorities; 

 that is, to give a cross section of the field complete enough to 

 introduce the reader to the subject. Hence the authors have 

 purposely omitted much material on the more common types 

 of fermentation with only typical references, while for more 

 uncommon types the treatment has been practically complete. 

 Since the purpose is not primarily historical many of the older 

 references have been omitted and later work cited. 



A survey was likewise made of the media and analytical 

 methods for each reference listed. This information will be 

 reserved for a further communication. However, a few general 

 remarks may be pertinent. For example, it is an open question 

 whether in some instances succinic acid is produced from the 

 non-nitrogenous substrate or is a secondary product resulting 

 from the breakdown of the cell or is due to the action upon 

 glutaminic acid. Oxidation and reduction (dehydrogenation 

 and hydrogenation) may in some instances be due to conditions 

 in the medium rather than to direct action of the living 

 organisms. The recent work of Conant and Aston (1928), for 

 example, has shown the production of acetone, carbon dioxide, 



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