BACTERIA DECOMPOSING UREA 213 



cent MgS0 4 was used to demonstrate that microorganisms, capable of 

 transforming hippuric acid, are present in the surface layer of the soil in 

 larger numbers and are more active than in the subsoil. 29 A medium 

 containing 1500 cc. water, 5 grams hippuric acid, 2 grams K ? HP0 4 and 

 1 gram MgS0 4 , neutralized with sodium carbonate, was also used 30 

 for the study of hippuric acid bacteria. Thirty-four species were iso- 

 lated from soil, manure, urine, etc.; of these, twenty-eight decomposed 

 hippuric acid and the others decomposed urea and uric acid. All those 

 bacteria that decomposed urea also decomposed uric acid and vice 

 versa; but those that decomposed hippuric acid did not necessarily 

 decompose urea and uric acid, and vice versa. 



Stapp 31 employed, for the isolation of uric and hippuric acid bacteria, the 

 following two media: 



I. Uric acid 0.5 gram II. KH 2 P0 4 0.50 gram 



Na 2 HP0 4 3.0 grams MgS0 4 0.25 gram 



Mineral solution 50 cc. Sodium hippurate 1.25 grams 



Water 450 cc. Water 500 cc. 



The mineral solution used in Medium I was that of A. Meyer: 



KH 2 P0 4 l.Ogram NaCl O.lgram 



CaCl 2 O.lgram Fe 2 Cl 6 0.01 gram 



MgSO^H^O 0.3 gram H 2 1000 cc. 



Portions of the solutions (50 cc.) were placed into 200 cc. Erlenmeyer flasks and 

 inoculated with soil or feces of various animals. Six species of bacilli were 

 carefully described. 



1. Bac. cobayae A. M. & S. a non-motile, spore-forming organism. The cells 

 attain a size up to 5.5/t long (usually 4/*) and 1 to 1.2/* in diameter. The ellip- 

 soidal to cylindrical spores, usually with convex poles, are 1.4 by 0.8/*. The organ- 

 ism forms diastase, protease, also H 2 S, tryptophane and skatol; nitrates are 

 reduced. 



2. Bac. capri A. M. & S. is without flagella, up to 6.2/* long and 1 to 1.1/* in 

 diameter; ellipsoidal or egg shaped spores are 1.4 by 0.8/*; reduces nitrates and 

 forms diastase. 



3. Bac. guano A. M. & S. is a motile rod, with peritrichic flagellation, up to 5.4/* 

 long and 0.7/t in diameter (2.8 to 3.4 by 0.6 to 0.7/*); the ellipsoidal spores are 

 1.4 by 0.8/*; weak reducing power, no diastase formation; gelatin is liquefied. 



4. Bac. musculi A. M. & S., with peritrichic flagellation, is 4.5 to 5 by 1 to 1.2/iJ 



29 Yoshimura, K. Note on the behavior of hippuric acid in soils. Bull. Coll- 

 Agr. Tokyo. Imp. Univ. 2: 221-223. 1895. 



30 Schnellmann, H. Uber die hippursaure-vergarenden Bakterien. Diss. 

 Gottingen. 1912. 



31 Stapp, C. Botanische Untersuchungen einiger neuer Bakterienspezies, 

 welche mit reiner Harnsaure order Hippursaure als alleinigem organischen 

 Nahrstoff auskommen. Centrb], Bakt r II, 51: 1-71. 1920. 



