FAMILY AZOTOBACTERIACEAE 



221 



nitrogen, and 2 per cent or more of basic 

 nitrogen. 



Optimum temperature 25 °C to 28 °C. 



Distinctive characters : Lack of a 

 brown pigment ; occasional fluorescence ; 

 growth in peptone broth containing 

 glucose. 



Source : Originally isolated from canal 

 water at Delft. 



Habitat: Occurs in water and soil. 



3. Azotobacter indicum Starkey and 

 De. (Soil Sci. 47, 337, 1939.) From L. 

 indict/a, of India. 



Rods: Ellipsoidal, from U. 5 to 1.2 by 1.7 

 to 2.7 microns when grown on nitrogen 

 free glucose agar. One of the distinctive 

 characteristics is the presence of two 

 large, round, highlj'' refractive bodies in 

 the cells, one usually at each end. Mo- 

 tile by means of numerous peritrichous 

 fiagella (Hofer. loc. cit.). Gram-nega- 

 tive. 



The organism grows slowly but in 

 time produces large amounts of slime. 



Has high acid tolerance, since it grows 

 from pH 3 to 9. 



Sucrose or glucose agar plates : Colonies 

 are colorless, round, very much raised, 

 and uniformly turbid, having much the 

 appearance of heavy starch paste. Af- 

 ter two weeks, a buff to light brown color 

 develop;. 



Mannitol agar slant : Grows very 

 poorly. 



Peptone agar slant with 0.5 per cent 

 glucose: Limited grayish growth. 



Nutrient broth : No growth. 



Liquid media generally : Turbidity 

 with some sediment. 



Fixes atmospheric nitrogen readily 

 with either glucose or sucrose as source 

 of energy. 



Aerobic. 



Optimum temperature: 30°C. 



Distinctive characters : Tolerance of 

 acidity, wide limits of pH tolerated, 

 abundant slime production, large glob- 

 ules of fat within cells. 



Source : Soils of India. 



Habitat : Soils. 



Appendix I : The relationship of the following species to the species placed in .420- 

 tobacler is not yet entirely clear. 



Genus Azotomonas Stapp. 



(Cent. f. Bakt., II Abt., 102, 1940, 18; not Azotomonas Orla-Jen.sen, Cent. f. Bakt., 



II Abt., 24, 1909, 484.) 



Rod to coccus-shaped aerobic bacteria, motile by means of 1 to 3 polar Hagella. Xo 

 endospores. No fat-like reserve food granules in the cells. Form acid and gas from 

 glucose, and other sugars and alcohols. Form indole. Chemo-heterotrophic. Many 

 carbon compounds other than sugars used as sources of energy. Active in the fixation 

 of atmospheric nitrogen. Live in soil. From Gr. azvus, not living. French, azote, 

 nitrogen; Greek, monas, a unit; M. L. monad. 



The type species is Azotomonas insolita. 



Azotomonas insolita Stapp. (Ab- microns. Motile with one to three polar 

 stracts of Communications, Third In- flagella. Gram-negative. 



ternat. Congr. for Microbiol.. Sect. VIII, 

 1939, 306; abst.in Proc. Soil Sci. Soc. of 

 America, 4, 1939, 244; Cent. f. Bakt., II 

 Abt., 102, 1940, 1.) From Latin insolilus, 

 unusual . 



Gelatin: No liquefaction. 

 Agar slant: Glistening white growth. 

 Agar colonics: Flat, whitish, edge 

 entire. Weakly fluorescent. 

 Broth : Strong turbidity. Sediment. 



Coccoid rods: 0.6 to 1.2 bv 0.6 to 1.8 Pellicle. 



