212 BACTERIAL OXIDATIONS AND REDUCTIONS 



he had not investigated. Logic' has drawn attention to the fact that the non-mannite- 

 fermenting dysentery strains arc distinguished from the mannite-fermenting strains 

 by inability to reduce nitrite. Pelz' pointed out that streptococci never reduce ni- 

 trates. More attention has been given in recent work to the reduction of compounds 

 of S generally in the form of studies of H2S production by bacteria. 



There is general agreement that most bacteria do not reduce sulphates or form 

 H2S from taurine (Sasaki and Otsuka/ Myers/ Burger^). Salkowski*" pointed out, 

 however, that whatever may occur in cultural experiment, it is certain that sulphates 

 are reduced in sewage with H^S formation, possibly under the influence of mixed cul- 

 tures, and Beijerinck^ described two anaerobes, capable of reducing sulphates, which 

 are found in the mud of Dutch harbor bottoms. 



It is not clear that evolution of H.S from media containing proteins is necessarily 

 evidence of the reduction of S-containing compounds. It is certain, however, that the 

 most vigorous production of H2S is carried on by bacteria which can be shown in other 

 ways to have strong reducing properties as, e.g., B. sporogenes. It has also been shown 

 that such bacteria as tend to produce II2S do so more freely if cystine is added to the 

 medium (Kondo,^ Sasaki and Otsuka,^ Myers, ^ Burger^), and it is altogether likely 

 that reduction of cystine to cystein is a preliminary to evolution of H2S. Burger, how- 

 ever, pointed out that nascent H does not liberate H2S from cystine unless in acid 

 solution, whereas bacteria normally grow in slightly alkaline solutions. There is, there- 

 fore, need for further investigation on this point. 



The statements of the different workers with regard to the capacity of different 

 bacteria to produce H2S from cystine and from protein are conflicting, but there is a 

 general agreement that most coliform bacteria, including the Proteus and B. fluo- 

 rescens liquefaciens groups, have this property. 



It is in connection with the reduction of dyes and biological products such as 

 hemoglobin derivatives that most of the work on bacterial reductions has been done. 

 Theobald Smith,' who was one of the earlier workers in this field, used methylene blue, 

 the dye which has been most used for this purpose, and concluded that all bacteria were 

 alike in their powers of redu-^ing it and that reduction took place only when the bac- 

 teria were in actual contact with the dye. Both statements were disputed shortly after- 

 ward by Muller,'" and although they are generally true in the sense that all bacteria 

 are possessed of reducing powers and that this power is especially exercised within the 

 body or on the surface of the bacteria, the trend of subsequent work has been to justify 

 Miiller's position. Von Liebermann," Wichern,'- and Carapelle''^ all bring forward 



' Logie, W. J.: J. Hyg., 10, 143. iqio; ii, ,36. igii. 

 = Pelz., E.: Centralbl.f. Baklerlol., Abt. I, Orig., 57, i. 1910. 

 3 Sasaki,T., and Otsuka, I.: Biochem. Ztschr., 39, 208. 191 2. 



■I Myers, J. T.: /. Bad., 5, 231. 1920. s Burger, M.: Arch.f. Hyg., 82, 201. 1914. 



^Salkowski, E.: Ztschr. f. phys. Cheniie, 83, 143. 1913^ 

 ' Beijerinck, W. M.: Verzamdde Gcscliriflen, 4, 24. 

 "^ Kondo, M.: Biochem. Ztschr., 136, 198. 1923. 



'Smith, Theobald: Centralbl.f. BakterloL, Abt. I, Orig., 19, iSi. 1896. 

 '" Muller, F.: ibid., 26, 801. 1899. 



" Von Liebermann, Jr., L.: ibid., 51, 440. 1909. " VVichern, H.: Arch.f. Ilyg., 72, i. 1910. 

 '^Carapelle, E.: Centralbl.f. Bakteriol., Abt. I, Orig., 47, 545. 1908. 



