236 UTILIZATION OF CARBOHYDRATES 



It has been shown' that departure from the glucose configuration renders the 

 resulting mono- or di-glucose acid and alcohol progressively less utilizable as a source 

 of energy for bacteria. In general, the more fastidious types are the ones which are 

 the more readily affected by departures from the simple hexose configuration. One 

 of the rather unexpected results which flowed from the study of this phenomenon 

 was the failure of members of the Staphylococcus aureus group and Micrococcus tetra- 

 genus to utilize either gluconic or saccharic acid. Glycuronic acid was not available 

 at the time these studies were made. Similar series were studied with mannose and 

 galactose as the starting-point. The members of these series most difficult of utiliza- 

 tion again were acids: manno-saccharic and mucic acid. Dulcitol, the hexatomic 

 alcohol of the galactose series, is optically inactive through internal compensation. 

 It is much less readily utilized for energy by most bacteria, and it possesses, largely 

 for this reason, diagnostic value as a reagent for distinguishing certain types of 

 organisms, notably many members of the Bacillus mucosus capsulatus group of 

 bacteria, which are versatile fermenters. 



Much more study will be required before the significance of the departure from 

 the glucose configuration in relation to protoplasmic utihzation is understood, but 

 at least one rather striking practical possibility has emerged, namely, the ability to 

 identify carbohydrates and their derivatives by the use of microbes. Experiments 

 already published^ indicate that not only may certain carbohydrates be detected 

 thus by bacterial means, but also mixtures of sugars and their derivatives may be 

 identified^ and even measured with considerable accuracy. As little as one-one-thou- 

 sandth of a per cent of a sugar in a mixture has thus been detected and estimated,^ 

 with considerable precision. Not the least interesting possibility inherent in these 

 studies is the bringing together of the field of pure chemistry, biochemistry, and 

 bacteriology in the exploration of one of the most fundamental of problems: the 

 chemistry of vital processes. 



BACTERIAL FERMENTATION OF CARBOHYDRATES 



The simplicity of structure and the monotony of structure of bacteria has had 

 even from the earliest pioneer days a peculiarly directing influence upon the lines of 

 development of bacteriology. Coincident with the recognition of the necessity for 

 supplemental criteria to the meager anatomical characteristics of microbes, attention 

 was early directed to chemical changes they might induce in suitable cultural media 

 to afford data upon which to identify them. In this manner Pasteur^ recognized 

 butyric acid, and Nothnagel^ and Brieger^ identified lactic, acetic, propionic, and 

 formic acids as well as carbon dioxide and hydrogen among the products of fermen- 

 tation of sugars by various microbes, and Escherich^ made surprisingly accurate 

 balance sheets for the metabolism of some of the more common bacteria. 



Influenced, doubtless, by long familiarity with the yeast plant, by the remarkable 



' Kendall, A. I., Bly, R., and Haner, R. C: /. Infect. Dis., 32, 377. 1923. 



» Kendall, A. I., and Yoshida, S.: ibid., p. 362. 1923. 



3 Kendall, A. I., and Yoshida, S.: ibid., p. 369. 1923, ^ Nothnaf;el, H.: loc. cil. 



■» Kendall, A. I., and Yoshida, S.: ibid., p. 355. 1923. i Brieger, L.: loc. cil. 



5 Pasteur, L.: loc. cil. * Escherich, T.: loc. cit. 



