232 BACTERIOLOGICAL CHEMISTRY 



I II 



( p-indole-ethyl alcohol). 



NH 



{(I) " Hydrocarbons," 



ll.CHa.CH.NHa.COOH > R.CHa.CHa.COOH > K.CHo.CHg + CO2 



These products arise as the result of reductive deamination 

 followed by decarboxylation, that is, by decarboxyla- 

 tion of the substituted propionic acid. This type of 

 breakdown occurs by the action of putrefactive bacteria 

 under anaerobic conditions. Glycine, for example, gives 

 methane. 



D. With Two or Three Carbon Atoms Less. 

 (a) Acids, 



K.CH^.CH.NHa.COOH > R.CH =CH.COOH > 



H2O 

 R.CO.CH2.COOH — > K.COOH + CH3COOH 



The substituted formic acids, R.COOH, with two carbon 

 atoms less than the original amino -acid arise by de- 

 composition of the unsaturated acid via the p-keto-acid. 

 For example, Salmonella paratyphi and Sal. schottmillleri 

 (B. paratyphosus- A and -B) under aerobic conditions 

 produce j^-hydroxy-benzoic acid from tyrosine and indole- 

 carboxylic acid from tryptophane : — 



CH2.CH.NH2.COOH COOH 



OH OH 



(tyrosine) Qj-liydroxy-benzoic 



acid) 



CH,.CH.NHo.COOH ^\ COOH 



NH NH 



(It-yijlol.lianc) (iinlulc-carbuxylic ;u;ii!) 



