ANAEROBIC BACTERIA 163 



is greatly injured in the complete absence of oxygen; however, Kiir- 

 steiner 7 demonstrated that both obligate and facultative anaerobes will 

 thrive well for a number of generations in atmospheres free from oxygen. 

 Free oxygen exerts an injurious effect upon obligate anaerobic bacteria, 

 as pointed out already by Pasteur, the degree of injury depending on 

 temperature, age and abundance of cells. 9 In the following pages, the 

 term "anaerobe" will be applied only to the so-called "obligate 

 anaerobes." 



The presence of suspended particles, especially in case of colloidal 

 suspensions, favors the growth of anaerobic bacteria possibly through 

 their oxygen absorption. 10 



The more recent studies on oxidation-reduction processes in the 

 growth of microorganisms have brought out the fact that only 

 those bacteria are capable of growing anaerobically, which are cap- 

 able of activating some constituent of the medium as a hydrogen 

 acceptor. Some bacteria, like B. vulgar e, can activate nitrate and can, 

 therefore, grow anaerobically in the presence of nitrate and certain 

 hydrogen donators ; Bad. coli and Bad. prodigiosum can activate nitrate, 

 fumarate, malate and aspartate and can grow anaerobically, in the 

 presence of any of these substances, and with glycerol as a hydrogen 

 donator. 11 Recent important contributions point to the lack of cata- 

 lase formation by anaerobic bacteria. 12 Peroxides are formed in the 

 aerobic growth of bacteria and these peroxides would become injurious 

 to the organisms if not for the catalase which is formed and which 

 rapidly breaks up the peroxide into inactive oxygen and water. The 

 anaerobic bacteria, which] are unable to form catalase are thus subject 

 to the destructive action of the peroxide when grown under aerobic 

 conditions. 



A number of indicators are employed for measuring anaerobiosis or 



9 Bachmann, 1912 (p. 164). 



10 Hata, S. Uber eine einfache Methode zur aerobischen Kulti vie rung der 

 Anaeroben mit besonderer Beriicksichtigung ihrer Toxinproduktion. Centrbl. 

 Bakt. I, 46: 539-554. 1908; v. Lennep, R. Folia Microb. 1: No. 3. 1913. 



11 Quastel, 1925 (p. 469). 



12 McLeod, J. M., and Gordon, J. Catalase production and sensitiveness to 

 H 2 2 among bacteria; with a scheme of classification based on these properties. 

 Jour. Path. Bact. 26: 326-331, 332-343. 1923; The relation between the reducing 

 powers of bacteria and their capacity for forming peroxide. Ibid. 28: 155-164, 

 147-153. 1925. 



