SELECTED PAPERS 



ly employed moulds have been replaced by others that are even more 

 satisfactory; and currently only those known as Rhizopus Delamar and 

 Mucor Boulard find application. 



Still dissatisfied with the results, Effront and Boidin have aimed for 

 still higher goals. They had found that in both the malt- and the amylo- 

 process powerful proteases are operative in addition to the amylases. 

 This causes the major part of the proteins present in the raw material 

 to be converted into simple, water-soluble nitrogen compounds that 

 are lost in the course of further operations. Moreover, even the use of 

 mould diastase requires a rather costly pretreatment of the starch- 

 rich material with steam under pressure. These investigators there- 

 fore attempted to prepare a potent diastase that can act on native 

 starch, and that leaves the proteins largely intact. In this manner the 

 nitrogenous material can be recovered after the alcohol has been dis- 

 tilled off, and used as fodder. They ultimately succeeded in finding the 

 desired biochemical catalyst in a specially adapted culture of Bacillus 

 mesentericus . If properly prepared, one unit weight of such a culture is 

 capable of hydrolysing 1,000 unit weights of starch. Following the 

 treatment with Bac. mesentericus the raw material is subjected to a brief 

 action by Rh. Delamar in order to produce exactly the minimum 

 amount of soluble nitrogen compounds needed for a good development 

 of the yeast during the third stage of the process. Thus one sees how in 

 Effront's modification of the amylo-process the entire conversion of 

 starch into alcohol is accomplished by the successive operations of 

 three different micro-organisms. 



Proceeding now to a consideration of some other biochemical con- 

 versions, I may state that for the technical manufacture of lactic acid 

 the fermentation method possesses a virtually undisputed monopoly. 

 Chapman estimates that in 1909 Germany produced no less than 1500 

 tons of lactic acid for export, over and above the amount used inside 

 the country. Also in Holland the commercial manufacture of lactic 

 acid has lately been introduced. 



Most intriguing is furthermore the history of the biochemical man- 

 ufacture of acetone. During the years of the great rubber boom chem- 

 ists in many countries tried to find a method for the manufacture of 

 synthetic rubber. The British chemist, Perkin, devised a procedure in 

 which butanol was used as the starting material. In conjunction with 

 this process the French bacteriologist, Fernbach, developed a method 



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