264 



THE FORMATION OF SLIME OR GUM BY 

 RHIZOBIUM LEGUMINOSARUM. 



By R. Greig-Smith, D.Sc, Macleay Bacteriologist to the 



Society. 



The production of slime by Rhizobium leguminosarum under 

 certain conditions of cultivation has been noted by many investi- 

 gators as a character of the composite microbe. In a paper which 

 was published in these Proceedings (1899, 653) a few references 

 are made to these. Thus Frank saw zoogloea forms and mucila- 

 ginous colonies, Kirchner described the colonies of the Soja-Bean 

 race as being like drops of paraffin, and Laurent said that old 

 gelatin colonies are slimy. With my experience of slime-forming 

 bacteria, I can now recognise the evidence of slime that I then 

 obtained upon nutrient glycerin-agar. 



The present research had its origin in the occurrence of Rhizo- 

 bium in the gum that exuded from a Macrozamia spiralis. The 

 Rhizobium was induced to produce its slime and from that a gum 

 was obtained, but as this was totally different from the natural 

 gum of the plant, it was evident that the organism had been 

 present accidentally. The importance of the gum-production, 

 however, had by this time impressed itself upon my attention, 

 and work was begun not only with this particular race but with 

 others obtained from Krai of Prague and from locally grown 

 leguminous plants. The investigation extended over a consider- 

 able time, and many of the results had to be rejected on account 

 of the relatively small yield of slime under certain conditions of 

 nutrition and physiological activity. 



It is accepted that the nodule-former has some relation with 

 the fixation of nitrogen by the members of the Leguminosce, and 

 many investigators have endeavoured to obtain a proof of this 

 fixation by the micro-organisms in artificial culture. With, I 



