A Sugar Bacterium. 



65 



" A Sugar Bacterium." By H. Marshall Ward, F.B.S., and 

 J. Keynolds Green, F.B.S. Eeceivecl March 2, — Bead 

 March 9, 1899. 



In the 'Annals of Botany ' for 1897,* one of us published a short 

 note on a curious organism — or rather association of organisms — 

 obtained in Paris, and said to have come from Madagascar, where it 

 occurs as " an excrescence on the sugar-cane." 



It consists of a bacterium associated with at least one yeast, and 

 grows in saccharine solutions, producing clumps so like the ginger-beer 

 plant f that the assumption seemed warranted that we had here a 

 symbiosis of the same kind as that proved to occur there. 



Moreover, the general course of events in the use of this body, which 

 is employed to make a fermented effervescing drink from common 

 brown sugar in water, points to the same conclusion. 



In moderately strong solutions containing 15 to 20 per cent, of 

 common sugar in water, the clumps referred to induce a powerful fer- 

 mentation, resulting in the liberation of relatively enormous quantities 

 of carbon dioxide and some acid, the saccharine liquid being thus 

 converted into a not unpleasant acid drink, with some resemblance 

 to lemonade or ginger-beer. 



From the fact that this fermentation occurs rapidly when the corked 

 flask is entirely filled with the recently boiled sugar solution, infected 

 with a few clumps of the organism, it is clear that oxygen is not 

 necessary in any quantity. 



This conclusion is also confirmed by the observation that if a bottle 

 of soda-water is opened, and a handful of sugar added with a few of 

 the clumps, and at once corked and wired, the pressure of the carbon 

 dioxide liberated during the active fermentation which at once ensues 

 becomes so great in three or four days at 22° C, as to cause danger of 

 bursting the flask ; and if a manometer tube with mercury is attached, 

 as described in the paper above referred to,{ the bubbles of gas pressed 

 out come off steadily for many days, or even weeks, at ordinary 

 temperatures, until no more sugar is left. 



The general resemblances to the well known kephir, also referred to 

 in the previous paper, led one of us to repeat the above experiments 

 with sugar and milk, instead of soda-water, with the result that carbon 

 dioxide came off as before until all the sugar had disappeared, the milk 

 meanwhile undergoing coagulation into clots, but since these clots 

 remained unaltered for weeks or months, this experiment suggests 



* Marshall Ward, " On the Gingpr-beev Plant," 1 Annals of Botany,' 1897, vol. ii, 

 p. 341. 



f ' Phil. Trans.,' B, 1892, pp. 125—197. 

 X Loc. ext., p. 137. 



F 2 



