CHAPTER VI 

 The Study of Obligately Anaerobic Bacteria^ 



L. S. McClung and Robert B. Lindberg 



It is impossible to list here all the methods which have been proposed 

 for the study of anaerobic bacteria; an attempt is made, however, to out- 

 line a number of technics which have been used widely and which should 

 ordinarily be suitable for routine studies of anaerobic species. Those 

 interested in other technics are advised to consult Sec. B of the sub- 

 ject index bibliography relating to the anaerobic bacteria (McCoy and 

 McClung, 1939; McClung and McCoy, 1941). The worker who has had 

 no experience with anaerobic bacteria should study some of the articles 

 which deal with principles of anaerobic culture or which record the results 

 of a study of a considerable number of strains: Fildes, 1931; Hall, 1922, 

 1928, 1929; Heller, 1921; Knorr, 1923, 1924; McCoy et al, 1926, 1930; 

 Mcintosh, 1917; Meyer, 1928; Reed and Orr, 1941; Spray, 1936; Zeissler, 

 1930; Zeissler and Rassfeld, 1928. Valuable suggestions in English 

 will be found in Smith (1955), and in French in Lehert and Tardieux 

 (1952). The recent literature has been reviewed by McClung (1956). 



The organisms which we call obligate anaerobes are those that require 

 a low (reduced) oxidation-reduction potential, which can be brought 

 about by exclusion or removal of atmospheric oxygen, alone or in com- 

 bination with chemical reducing agents added to the medium. It is not 

 easy to answer the question of the best method of determining whether or 

 not a given organism is an obligate anaerobe. The catalase reaction, 

 when applied to pure culture, gives presumptive evidence, for obligate 



1 The methods and technics suggested herein are those recommended for use with 

 the more common sporeforming anaerobic species. Many of these methods are suit- 

 able also for the study of the nonsporeforming types, but for the present no attempt 

 will be made to outline particular methods of study for these. If the technics herein 

 outlined do not prove satisfactory, the worker interested in the pathogenic nonspore- 

 formers should consult the review of Dack (1940) and the books by Pr6vot (1948, 

 1955) and Smith (1955). Nonpathogenic types exist, as for example, the methane 

 organisms discussed by Barker (1936). For the complete literature on all types 

 refer to Sec. Id (nonsporeformers) in the bibliography of McCoy and McClung 

 (1939) and McClung and McCoy (1941). 



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