542 ENZYMES DECOMPOSING SACCHARINES. 



777. , 8. ellipsoideus and S. crater icus, ferment dextrin more or less 

 strongly ; of thirty-one other wild races examined, thirteen pure 

 cultures were found to liberate carbon dioxide, faintly or decidedly, 

 from dextrin solutions. 



Of other organisms that ferment dextrin, mention may be 

 made of : S. exiguus, Monilia Candida, Mon. vuriabilis, Sachsia 

 suaveolens, Mucor Rouxii, Amylomyces (3 and Am. y, Logos yeast, 

 Schizos. Pombe, Schizos. mellacei, and Schizos. octosporus. This 

 carbohydrate is also attacked by a series of yeasts from Danzig 

 Jopen beer. 



According to P. Lindner's researches, no definite rule exists 

 with reference to the fermentability of the dextrins by special 

 yeasts; and it is urgently necessary that these investigations 

 should be continued under the conditions laid down by C. J. 

 Lintner, namely, the use of pure cultures and pure dextrins 

 exclusively. The former condition was fulfilled by Lindner, but 

 the solution of the second problem is complicated by the circum- 

 stance that, in spite of all that has been done, the dextrins 

 resulting f rom the action of diastase on starch have not yet been 

 isolated in the form of scientifically pure chemical entities. 



However this may be, we may assume that the dextrins are 

 not directly fermentable by yeasts, but that, like all polysaccha- 

 rides, they must first be split up into directly fermentable sugars 

 by the action of an enzyme. This enzyme, which has been named 

 amylase, was found by KATZ (II.) in various mould fungi, includ- 

 ing species of Penicillium and Aspergillus (see p. 353, vol. ii.), as 

 also in Bact. megaterium. Our knowledge of the amylase of yeast 

 is at present very scanty, and much work is needed to amplify it. 



Having now become acquainted with the present state of 

 affairs with regard to the fermentation of dextrin, we are able to 

 understand the patent taken out by EFFRONT (XV.) for the 

 cultivation of yeast possessing the power of fermenting that 

 substance. According to the inventor, certain beer yeasts that 

 are capable of slightly fermenting dextrin can have their powers 

 in this respect considerably augmented by cultivation under 

 favourable conditions. The yeasts are first grown in a medium 

 that contains aldehyde, in addition to dextrose and mineral 

 substances (potassium nitrate). After preparation in this manner, 

 they exhibit a decided tendency to ferment dextrin; and this 

 property can be further intensified by suitable treatment. The 

 scientific explanation of the Effront process may be sought in two 

 directions ; either each beer yeast contains a dormant enzymogen, 

 which can be stimulated to an increased production of amylase by 

 suitable treatment, or else the method of cultivation (perhaps 

 by spontaneous infection) favours certain yeasts that already 

 produce amylase, so that they gain predominance in the cultures, 

 under the conditions of environment selected by Eftront, obeying 

 the law of natural pure culture as established by Delbruck. No 



