232 



A GUM BACTERIUM FROM A KUCALYPT, 



The bacterium differs absolutely morphologically from Bac. 

 levaniformans, the organism which occurs in cane-juice, and in 

 raw and refined sugars; and it is interesting that the same gum 

 should be formed by two widely differing species of bacteria. 

 The specific characters of the bacterium, which I have named 

 Bacterium eucalypti^ are given at the end of this paper. 



In testing the various points connected with the growth of the 

 organism, it was found that growth occurred at 22°, 30°, and 37° C. 

 The bacterium did not appear to have a preference for either of 

 the higher temperatures; the growths appeared equally copious, 

 although at 37° it was dry and stiff, while at 30° it was moist 

 and flowing. A faintly acid medium (acidity = 0-075% tartaric 

 acid) enables the organism to grow better, and to produce more 

 gum than neutral or slightly alkaline media. Saccharose and 

 raffinose («.p'., Eucalyptus manna) are the only carbohydrates 

 from which the bacterium appears to form gum. No levan was 

 produced, and the growth was always scanty when dextrin, 

 starch, levulose, dextrose, lactose or maltose was substituted for 

 saccharose in the medium. 



The composition of the fluid saccharose culture* as regards 

 sugars and gum was tested in the manner described in a former 

 paper t at the end of one, nine and nineteen days. The results 

 are calculated upon 100 parts of saccharose which the medium 

 contained in the litre, and due allowance has been made for the 

 evaporation of the culture fluid daring its incubation at 30°. 



Production of Levan and Reducing Sugars from Saccharose. 



* Saccharose 100, peptone 10, potassium chloride ,'), sodium phosphate 2, 

 tap water to 1000. 



t These Proceedings, 1901, Pt. iv., o93. 



