256 DIFGO MANUAL 



metabolism and nutrition, but also with the difficulties attendant upon the 

 separation, classification and recognition of bacterial species by means of specific 

 cultural reactions, have long demonstrated that no single peptone can be equally 

 suitable for all the varied ends in view. Indole production, maintenance of 

 growth, maximum production of soluble toxins, etc., are all definitely influenced 

 by the nature and character of the peptone and the other nitrogenous constitu- 

 ents of the culture medium. 



Recognizing the essential importance and great practical value of these facts 

 in relation to bacteriological investigations, Difco Laboratories has for many years 

 engaged in a consistent and progressive study of this problem, the fruits of which 

 are represented in the group of products briefly described below. These products 

 are the results of original, intensive investigations, checked and corroborated by 

 extensive practical trials in the hands of experienced bacteriologists before such 

 materials are released for distribution. It is believed that they represent a definite 

 advance in practical bacteriology and that they cover, as fully as is possible at 

 present, the field of peptones in their relation to microbiology. 



B AGTO-PEPTONE ( B 11 8 ) 



Bacto-Peptone, first introduced in 1914, has long since become the universal 

 standard peptone for the preparation of bacteriological culture media. Countless 

 studies which have been published during the intervening years specify the use 

 of Bacto-Peptone and constant reference to its use is currently being made in 

 bacteriological literature. 



When Bacto-Peptone was originally developed it was first subjected to trial 

 in the routine bacteriological examination of water and milk, and was shown to 

 be well suited for these purposes. It has continually been recommended as the 

 peptone to be employed for culture media preparation in "Standard Methods of 

 Water Analysis" and is at the present time included in the Ninth Edition.^ It is 

 similarly specified for use in a number of special studies of milk and other dairy 

 products. 2'^ Bacto-Peptone, furthermore, is also suggested for general use in the 

 preparation of culture media in "Standard Methods"* of the Division of Labora- 

 tories and Research of the New York State Department of Health. 



Bacteriological literature abounds with an increasing number of references 

 to the use of Bacto-Peptone, not only for the preparation of general culture media, 

 but also for those employed in special research studies. Marbe and Olariu^ have 

 employed Bacto-Peptone in combination with Proteose Peptone in their medium 

 for the elaboration of toxin by Corynehacterium diphtheriae. Veldee^ also em- 

 ployed a combination of these two peptones in his medium for cultivating strep- 

 tococcus for scarlet fever toxin. He states that his medium gives a toxin of 

 uniformly high potency and that it is particularly suitable for the preparation of 

 purified and tannic acid precipitated toxin. Bacto-Peptone is also used in culture 

 media for studies of the intestinal bacteria,^ ^° ^^ streptococci,^^ *° ^^ pneumo- 

 cocci,^^ lactobacilli,26 anaerobes^^'^^'^^ and the fungi. ^^-^^ It has been suggested 

 for use in media for the Brucella,^--^^ but is now superseded by Bacto-Tryptose 

 for this purpose. Bacto-Peptone is also specified in media used in studies of bac- 

 terial metabolism,^* studies of disinfectants and determinations of phenol coeffi- 

 cients,^^ studies of bacterial luminosity,^^ and the reduction of nitrates. ^^ Al- 

 though it has been suggested for use in media for detection of hydrogen sulfide 

 productions^ its use for this purpose has been supplanted by Bacto-Tryptone and 

 Proteose Peptone. Similarly, for pigment production, Proteose Peptone or Bacto- 

 Tryptone is more satisfactory than Bacto-Peptone as recommended in earlier 

 papers. s^'*^ 



