Biochemistry. — „Concerning the Synthetic Action of Bacteria in 

 the Paunch of the Coiu". By Prof. B. Sjoi.lema and J. E. van 

 DER Zande. (Communicated by Prof. H. Zwaardemakek). 



(Gommunicated at the meeting of December 30, 1922). 



The question whether bacterial processes occurring in the paunch 

 of ruminants are significant for the metabolism of these amimals^), 

 should be given more attention to than heie to fore, since, by way of 

 trial, ruminants are fed with urea, made from the nitrogen in the 

 air. For the significance of the sulbstitution of urea for protein in 

 the animal's diet depends to a great extent on the capacity of the 

 bacteria of the paunch to synthesize from urea, in the presence of 

 non-nitrogenous substances, the amino-acids which the higher animals 

 are not able to build up. 



Tryptophane is one of the amino-acids indispensable to man and 

 to the higher animals. It is highly impi-obable that mammals can 

 synthesize tyrosine from non-aromatic substances. 



We have tried to ascertain v\ hether these two substances can be 

 built up by the bacteria occurring in the cow's paunch, when, 

 beyond ammonia no other source of nitrogen is present tluin urea, 

 asparagin or aspartic acid. . 



Our procedure was as follows:") 



Directly when the animal was killed, part of the contents of the 

 paunch was brought to our Laboratory in a sterile bottle, fitted 

 with a glass stopper*). 



With the help of a sterile wire a little of the paunch contents 

 (i.e. of the turbid fluid after removal of the coarser particles) was 

 transmitted to sterile nutrient solutions, contained in Erlenmeyer- 

 flasks plugged with cotton-cool, and vv^hich were of a depth of 1 



1) Here we refer to the development of volatile acids in the paunch from sugar, 

 as demonstrated before by one of us (B. S.). See Bericht III 5*^ International. 

 Congres fiir "angewandle Chemie" Berlin 1903, p. 825. 



-) It was adopted because bacterial growth could not easily be recognized 

 directly in the turbid juice of the paunch (even when much diluted), and also 

 because we wanted quantitative data regarding tryptophaneformation. 



3) We would here gratefully acknowledge our thanks to Mr. Hoefnagel and to 

 Mr. DE Graaf, respectively director and sub-director of the Utrecht abattoir, for 

 their kind assistance in obtaining the material required for these experiments. 



