MUCOR. 209 



different species in regard to the production of alcohol. The 

 same rules which govern yeast fermentations seem on the whole 

 to apply to these processes. Thus, according to Wehmer, 

 when the general conditions are favourable, in presence of 

 oxygen and at a medium temperature, the fermentation is 

 practically completed in the course of a few days. A re- 

 markable feature of the fermentation produced by these fungi 

 is that the liquid remains clear throughout the operation. 



Some of the results obtained during Hansen's investiga- 

 tions may be quoted to show the difference in the productivity 

 of the various species. 



M. erectus possesses the greatest fermentative activity. 

 In beer- wort of ordinary concentration (14- 15 Balling), 

 it yields up to 8 per cent, by volume of alcohol. It also 

 induces alcoholic fermentation in dextrin solutions, and con- 

 verts starch into reducing sugar. Mucor spinosus yields up 

 to 5-5 per cent, by volume of alcohol in beer-wort. In maltose 

 solutions distinct fermentation phenomena were observed, and 

 after the lapse of eight months the liquid contained 3-4 per 

 cent, of alcohol. Mucor Mucedo has a comparatively feeble 

 fermentative power both in wort (up to 3 per cent, of alcohol) 

 and in maltose and dextrose solutions. Mucor racemosus 

 produces as much as 7 per cent, of alcohol in wort, develops 

 invertase, and ferments the inverted cane sugar ; thus, like 

 the two species above mentioned, it occupies a particular 

 position. 



According to Gayon, Mucor circinelloides exercises a very 

 powerful action on invert sugar (yielding 5-5 per cent, by 

 volume of alcohol). According to Wehmer, M. javanicus 

 produces 4 to 5 per cent, of alcohol in a few days. 



Whilst the Mucor species are of no technical importance 

 as alcohol producers, those possessing powerful diastatic 

 enzymes, capable of converting starch into sugar, occupy an 

 important place in industry. It has already been mentioned 

 that they have been used by the Asiatic races for centuries. 

 Their systematic use in Europe began in 1892, when Calmette 

 isolated M . Rouxii from " Chinese yeast." The diastatic 

 enzyme of this fungus reacts most powerfully at 35-38 C. 

 and produces chiefly dextrose. The process, carried on as it 



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