MICROBIAL METABOLISM AND ITS INDUSTRIAL IMPLICATIONS 



from glucose. It is the great merit of Stacey to have first considered its 

 industrial production and the industry both in England and Sweden 

 has recently increased greatly in importance, owing to the discovery 

 made by Ingelman and Gronwall that partially hydrolyzed dextran 

 is a valuable substitute for blood plasma. 



The production of certain vitamins offers another example. Vita- 

 min B 2 or riboflavin, both in the pure form and as riboflavin con- 

 centrates, is being used increasingly for the fortification of fodder and 

 in the U.S.A. of human food also. By far the greater part of this ribo- 

 flavin is being produced by growing the fungus Eremothecium ashbyi 

 under suitable conditions. This organism can be made to synthesize 

 riboflavin so much in excess of its own needs that the vitamin crystal- 

 lizes in the cell and is partly excreted into the medium. It is worth 

 mentioning that for the isolation or concentration of the riboflavin 

 from the fermented mash, use is often made of a second micro-organ- 

 ism which converts the vitamin into its practically insoluble hydro- 

 genation product. 



Also, for the production of Vitamin B 12 , either pure or as a con- 

 centrate, and of the closely related animal protein factor, certain 

 actinomycetes and bacteria are being cultivated on an increasing scale. 

 Since in this production a yield of i mg per litre is apparently still 

 considered to be quite satisfactory, there seems to be ample room for 

 improvement in production methods. 



However, several of these products could also be manufactured 

 from raw materials of animal or vegetable origin. It is important that 

 it has become increasingly clear, of late, that certain micro-organisms 

 produce highly specific compounds, albeit in small quantities only; 

 moreover, some of these products are able to render eminent services 

 to mankind. I refer to the antibiotics, the large-scale production of 

 which has given a tremendous impetus to the development of industrial 

 microbiology in the last decade. 



The amazingly strong biological action of certain microbial metab- 

 olic products had been established long before the word antibiotic 

 was coined. Almost from the beginning of microbiology it has been 

 known that the fatal influence which certain bacteria exert on man 

 or animal is due to the excretion by the bacteria of some product 

 which in an extremely low concentration is toxic to the host. The 

 isolation by a group of American investigators of some of these bacte- 



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