HETEROTROPHIC BACTERIA REQUIRING COMBINED NITROGEN 155 



The bacteria of the so-called colon group found abundantly in the 

 feces of warm blooded animals differ, in certain cultural characteris- 

 tics, 28 from those found in the soil, the former being largely Bad. coli 

 and the latter belonging to the Bad. aerogenes group, which is even cap- 

 able of fixing small amounts of nitrogen. Out of 467 strains of bacteria 

 isolated from various soils by Chen and Rettger, 430 were identified as 

 Bad. aerogenes, 17 as Bad. cloacae and only 20 as Bad. coli; the sources 

 of the Bad. coli strain were shown by a sanitary survey to be not entirely 

 free from animal pollution. However, all of 173 organisms found in the 

 feces of various animals were typical Bad. coli. When Bad. coli and 

 even Bad. aerogenes are added to the soil in considerable numbers, they 

 rapidly die out, 29 since conditions are not very favorable for their 

 development, although Bad. coli was found 30 to survive in the soil for 4 

 years. 



It is of interest to note here that Stoklasa 31 found the following 

 organisms in the "rhizosphere" or in close proximity to the root 

 system of plants, consisting largely of non-spore-forming bacteria: 



Bad. acidi laclici a and /3 



Bad. pneumoniae 



Bad. coli group 



Bad. proteus vulgaris 



Bad. ochraceum 



Bad. fulvum 



Bad. pundatum 



Bad. putidum 



Bad. fluorescens liquefaciens 



Bad. anthracoides 

 Azotobader chroococcum 

 Butyric acid bacteria 

 Bac. mycoides 

 Bac. mesentericus 

 Mycoderma 



Cladosporium herbarum 

 Fusarium 



Thermophilic bacteria. It has been known since the work of Globig, 32 



28 Chen, C. C., and Rettger, L. F. A correlation study of the colon-aerogenes 

 group of bacteria, with special reference to the organisms occurring in the soil. 

 Jour. Bact. 5: 253-298. 1920; Levine, M. Bacteria fermenting lactose and their 

 significance in water analysis. Iowa Engin. Exp. Sta. Bui. 62. 1921. 



29 Skinner, C. E., and Murray, T. J. The viability of B. coli and B. aerogenes 

 in soil. Jour. Inf. Dis. 38: 37-41. 1926. 



30 Young, C. C, and Greenfield, M. Observation on the variability of the 

 Bacterium coli group under natural and artificial conditions. Amer. Jour. Publ. 

 Health, 13: 270-273. 1923. See also Koser, S. A. Coli-aerogenes group in 

 soil. Jour. Amer. AYater Works Assn. 15: 641-646. 1926. 



"Stoklasa, 1926 (p. xiii). 



"Globig. Uber Bakterienwachstum bei 50-70°. Ztschr. Hyg. 3:294-321. 



