400 MICRO-ORGANISMS AND FERMENTATION. 



ferment lactose, galactose, cane-sugar, glucose, invert-sugar, 

 and finally maltose, but the last only with great difficulty. 

 In the fermentation of milk-sugar with these yeasts, the 

 resulting liquids are as rich in alcohol as the strongest beers. 

 Kayser remarks that it may, perhaps, be possible to make 

 practical use of this observation and by means of these fungi 

 convert the large quantities of whey, obtained in the manu- 

 facture of cheese, into an alcoholic liquor. 



Beijerinck has described two yeasts which also ferment 

 lactose, and which must be provisionally regarded as non- 

 Saccharomycetes ; these are Saccharomyces Kephyr, which occurs 

 in kephir-grains and consists of longish cells of varied shape, 

 and forms slightly jagged colonies liquefying gelatine ; and 

 Saccharomyces Tyrocola (from Edam cheese), which consists 

 of small roundish cells, and forms snow-white colonies on 

 gelatine. Beijerinck found that these two species secrete a 

 particular invertive ferment (lactase) which inverts not only 

 cane-sugar but also lactose ; it does not, however, invert 

 maltose. It is stated that lactase may be prepared as follows : 

 A 5 per cent, solution of lactose, containing nutrient salts 

 and asparagin, is fermented with kephir-yeast ; the product 

 is filtered and the ferment is precipitated from the filtrate by 

 the addition of alcohol. According to Schuurmans Steckhoven, 

 however, the enzyme of Beijerinck's kephir-yeast does not 

 invert lactose. 



In Lombardy Grana cheese a unilaterally budding top- 

 fermentation yeast was discovered by Bochiccio, which is 

 called Lactomyces inflans caseigrana. The growth consists of 

 round, ellipsoidal, and oblong cells, and forms whitish colonies 

 on gelatine, with smooth edges. No spore-formation was 

 observed. In lactose-broth it produces a vigorous fermenta- 

 tion at 25 to 40 C. ; the best temperature for the develop- 

 ment is about 30 C., the limit of existence at about 60 C. 

 Whey infected with this species is converted into a foaming 

 beverage of a somewhat agreeable taste. 



Weigmann has isolated a pure culture of Torula from a 

 defective butter. By fermentation in milk 51-2 per cent, by 

 weight of alcohol and 34-4 per cent, of carbon dioxide, together 

 with 3-6 per cent, of butyric acid were produced. Orla Jensen 



