CHAPTER XVIII 



GAS METABOLISM OF BACTERIA 



M. H. SOULE 



Hygienic Laboratory, University of Michigan 



INTRODUCTION 



It is questionable whether any gas other than oxygen is absolutely necessary for 

 the activities of the cell. The fixation of atmospheric N2, the oxidation of H2S to S 

 and H2O, etc., are activities independent of the main function of respiration. The 

 working hypothesis has been laid down that CO2 is essential as a stimulus for the 

 growth of organisms. It will be shown later that this hypothesis probably holds true for 

 all organisms just as this gas is required for the life of the higher animals. It is not 

 utilized as a source of food or energy but it maintains a physico-chemical equilibrium 

 within the cell. 



The study of gas changes produced by micro-organisms is of rather recent date. 

 The combustion theory of respiration initiated by Lavoisier' was extended to all kinds 

 of animals by Spallanzani,^ and was developed by Pasteur (1859, 1861 ff.) in his work 

 on fermentations. This was followed by many isolated studies such as those of Buch- 

 ner^ on the Fitz bacillus and of Escherich^ on B. coli and B. lactis aero genes. Hesse^ 

 demonstrated CO2 production and O2 absorption by eight organisms which were not 

 of the aerogenic type. These results were questioned at first by Scheurlen,^ who 

 denied that bacteria, like animals, could respire and, with Buchner, he thought that 

 CO2 was the result of the action of acids on the carbonates of the medium. Eventu- 

 ally, however, he confirmed Hesse's work by finding that every one of one hundred 

 and forty-one strains of bacteria which he examined produced CO2. In the meantime, 

 Winogradsky^ had conclusively proved that certain bacteria fix atmospheric nitrogen 

 — a fact indicated many years before by the work of Berthelot^ on soils. The pres- 

 ence of CH4, N2, H2, and H2S in intestinal gases had been reported by various ob- 

 servers as mentioned by Escherich,' but exact quantitative determinations of the gas- 

 eous metabolism of the organisms producing these substances have not been made. 



The early methods employed in the study of gas changes by bacteria were some- 



' Lavoisier, A. L.: Hist, et Mem. de I'Acad. de sc. Paris, 17S0; Mem., Annee, p. 185. 1777. 



* Spallanzani, L.: Dissertazioni Varie, Memorie sidla Respirazione, Vol. 2. 1826. 



3 Buchner, E.: Zlschr.f. phys. Chemie, 8, 367-90. 1884. 



■f Escherich, T. : Die Darmbahlerien des Sdiiglings und ihrc Beziehiingcn zur Physiologic der 

 Verdauung, pp. 128-33. Stuttgart: Enke, 1886. 



s Hesse, W.: Ztschr. f. Hyg. u. Infeklionskrankh., 13, 17-37; 183-91- 1S93; 25,477-81. 1897; 

 Arch. f. Hyg., 2S, S07 -11- 1897. 



^ Scheurlen, E.: Arch. f. Hyg., 26, 1-29. 1S96; Inkrnat. Beilr. 2; inn. Med. zur Feicr jo jdhrigen 

 Gehurtstages E. von Leyden, 2, 205-7. Berlin: Hirschwald, 1900. 



' Winogradslcy, S.: Compt. rend. Acad. Sc, 116, 1385. 1893. 



SBerthelot, M.: ibid., 85, 178. 1877. » Escherich, T.: loc. cit. 



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