252 



BACTERIOLOGICAL CHEMISTRY 



Proskauer reaction, it lias been demonstrated that the 

 Voges-Proskaiier reaction depends on tlie production of 

 acetyl-methyl-carbinol, or acetoin, CH3CO.CHOH.CH3, 

 which, in the presence of potassium hydroxide becomes 

 oxidised to diacetyl, CH3CO.CO.CH3, which reacts with 

 some substance in the peptone containing a guanidine 

 NH.3 



residue, C==NH , to give the red-coloured compound. 



^NHR 

 The formation of acetoin by Voges-Proskauer positive 

 organisms like Aerohacter aerogenes follows the scheme 

 below, suggested by Kluyver : — 



CH20H.CH.(CIiU^i)3CH0H (gluccse) 







Na^HPO^ 



(methylglyoxal 

 hydrate) 



1 molecule 



i 



HCOOH + CH3.CHO 



i 



H2 + CO2 



/OH 

 -OH 

 H 



CH3.CHOH.COOH 



(lactic acid) 



1 molecule 



2H + CH3.CO.COOH (pyruvic 

 I acid) 



€H3.CH0 + CO2 



(acetoin) CH3.CHOH.CO.CH3 



\ reduction 

 CH3.CHOH.CHOH.CH3 



(2 : 3-butyleno-glycol) 



r i 



I CHo.CH. 



OH 



