FAMILY II. RHIZOBIACEAE 



287 



Usually smaller than in Rhizobium legumi- 

 nosarum and R. trifolii. Gram-negative. 



Growth on mannitol agar is rapid with 

 tendency to spread. Streak inoculation is 

 raised, glistening, semi-translucent, white, 

 slimy. Occasionally mucilaginous, but this 

 character is not so marked as in Rhizobinni 

 trifolii. 



Very slight acid formation from glucose, 

 galactose, mannose, sucro.'^e and lactose. 



Aerobic. 



Optimum temperature, 25° C. 



Source: Isolated from root nodules of 

 Phaseolus vulgaris (kidney bean), P. angusti- 

 folius (bean) and P. multiflorus (scarlet 

 runner) (Burrill and Hansen, 111. Agr. Exp. 

 Sta. Bui. 202, 1917, 137). 



Habitat: Widely distributed in the soils 

 In which beans are grown. 



3. Rhizobium trifolii Dangeard, 1926. 

 (Le Botaniste, Ser. 16, 1926, 191.) 



tri.fo'li.i. L. noun trifoliuni clover, tre- 

 foil; M.L. neut.n. Trifolium generic name 

 of clover; M.L. gen. noun trifolii of clover. 



Rods. Motile by means of peritrichous 

 flagella. Bacteroids from nodules are pear- 

 shaped, swollen and vacuolated, rarely x- 

 or y-shaped. Gram-negative. 



Growth on mannitol agar is rapid. The 

 colonies are white becoming turbid with 

 age. Frequently mucilaginous. Streak cul- 

 tures transparent at first. Growth mucilagi- 

 nous, later flowing down the agar slant and 

 accumulating as a slimy mass at the bottom. 

 Produces large amounts of gum. 



Slight acid production from glucose, ga- 

 lactose, mannose, lactose and maltose. 



Aerobic. 



Optimum temperature, 25° C. 



Source: Isolated from root nodules of 

 species of Trifolium (clover). 



Habitat: Widely distributed in the soils 

 where clover grows. 



4. Rhizobium lupini (Schroeter, 1886) 

 Eckhardt et al., 1931. {Phytomyxa lupini 

 Schroeter, in Cohn, Kryptogamen-Flora 

 von Schlesien, 3, I, 1886, 135; Eckhardt, 

 Baldwin and Fred, Jour. Bact., 21, 1931, 

 273.) 



lu.pi'ni. L. noun lupinus the lupine; M.L. 



mas.n. Lupinus generic name of lupine; 

 M.L. gen. noun lupini of Lupinus. 



Rods. Motile by means of 1 to 4 flagella, 

 usually 2 or 3. Bacteroids are vacuolate 

 rods, seldom if ever branched. Gram-nega- 

 tive. 



Growth on j-east water, mannitol agar is 

 scant to moderate with alkaline reaction. 



Beef -peptone gelatin: Little growth with 

 extremely slow liquefaction. 



On galactose an alkaline reaction serves 

 to differentiate Rhizobium lupini from all 

 fast-growing rhizobia (R. phaseoli, R. rneli- 

 loti, R. trifolii and R. leguminosarum) . An 

 initial alkaline reaction followed more 

 quickly by an acid reaction on rhamnose 

 and xylose separates R. lupini from slow- 

 growing R. japonicum and the Rhizobium 

 sp. from cowpea. 



In general Rhizobium lupini produces 

 slight to moderate acidity on pentose sugars 

 and no change or alkaline reaction on hex- 

 oses, disaccharides or trisaccharides. 



Litmus milk: No serum zone; no reduc- 

 tion; slight alkaline reaction. 



Meager growth on potato and parsnip 

 slants and on carrot agar. 



Aerobic. 



Optimum temperature, 25° C. 



Source: Isolated from root nodules on 

 Lupinus (lupine), Serradella and Orniihopus. 



Habitat: Widely distributed in soils in 

 which these legumes grow. 



5. Rhizobium japonicum (Kirchner, 

 1895) Buchanan, 1926. (Rhizobacterium ja- 

 ponicum Kirchner, Beitrage z. Biol. d. Pflan- 

 zen, 7, 1895, 213; Buchanan, Proc. Iowa 

 Acad. Sci., 83, 1926, 81.) 



ja.po'ni.cum. M.L. adj. japonicus of 

 Japan. 



Rods. Motile by means of monotrichous 

 flagella. Bacteroids of nodules are long and 

 slender with only occasional branched and 

 swollen forms. Gram-negative. 



Growth on mannitol agar is slow and 

 scant. The streak is slightly raised, glisten- 

 ing, opaque, white, butyrous, with little 

 gum formation. 



Pentose sugars give better growth than 

 the he.xoses. 



Little if any acid formed from carbohy- 



