Ingredients of Culture Media 



The choice of the ingredients to be used is most important for the successful 

 preparation of microbiological culture media. Superior products will yield su- 

 perior media and will lessen the time-consuming labor incident to their prepara- 

 tion. 



The ingredients listed in this section are prepared expressly for use in making 

 microbiological culture media. Each product is carefully tested for its usefulness 

 and suitability for the purpose for which it is intended. 



PEPTONES, DIFCO 

 ENZYMATIC HYDROLYSATES 



Peptone prepared expressly for bacteriological purposes was first introduced 

 by Difco Laboratories in 1914 after many years of preliminary study. The first 

 of our bacteriological peptones to be produced was Bacto-Peptone. This was 

 followed several years later by Proteose Peptone, Difco, and in more recent 

 years other peptones have been added to the group. Since no one peptone is 

 satisfactory for all microbiological purposes each of these peptones is particularly 

 suitable for some special purpose or possesses singular characteristics which dis- 

 tinguish it from other peptones. For this reason it has been the consistent policy 

 of Difco Laboratories to keep unchanged the method of preparation of its 

 bacteriological peptones once these products have become established. Slight 

 modifications or changes in method might readily result in products possessing 

 entirely different nutritive properties. Bacto-Peptone and other Difco peptones are 

 prepared today in the same manner as when first developed. Users of Difco 

 peptones are, therefore, assured of products prepared in a uniform manner at all 

 times. 



It is not improbable that increased knowledge of the minutiae of bacterial 

 metabolism may make it necessary to prepare additional specialized peptones in 

 the future, since the formula of a Difco peptone is never modified after once be- 

 ing adopted. For this reason Difco Laboratories is continuing its investigation, in 

 cooperation with other bacteriologists, to develop new products which will meet 

 the new demands. To this end, not only are extensive studies inaugurated and 

 carried on by Difco Laboratories, but many more are conducted in conjunction 

 with bacteriologists throughout the world, and we extend to all our active 

 cooperation to aid in the development of the peptones necessary to meet the 

 problems encountered in this field. 



It has been our consistent effort to make available, to the bacteriologist, 

 products which are eminently fitted and suitable for specific purposes in view. 

 Only when these preparations have been tested by extensive and impartial investi- 

 gation in the hands of laboratory workers are they released for general use. 



Difco peptones may be relied upon for biochemical studies, particularly fer- 

 mentation reactions because of their freedom from fermentable substances which 

 would interfere with the accuracy of such determinations. 



Practical experience, concerned not only with the complexities of bacterial 



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