TNDUSTRTAT. FERMENTATIONS 321 



(5) 3-t'husphiigly<erir acid — >■ phos])ho|iyruvi<: acid. 



aiul phosphoglyccromutase 



(6) Phosphopyruvic acid + adenosine diphosphate > pyruvic 



acid + adenosine triphosphate. 



lactic 



(7) Dihydroeo-enzyme I + CH3.CO.COOH > Co-enzyme I -f 



(pyruvic acid) enzyme 



CH3.CHOH.COOH 

 (lactic acid) 



Alternatively : — 



B. (1) Hexose diphosphate > 2-glycerophosphate. 



dehydrogenase 



(2) Glycerophosphate + 2 cytochrome > glyceraldehyde- 



phosphate + 2 reduced cytochrome. 



Cytochrome 



(3) 2 Reduced cytochrome + 0^— > 2 cytochrome + 2H2O. 



oxidase 



(4) Glyceraldehyde phosphate > methylglyoxal + phosphate. 



(5) CH3CO.CHO + H2O glyoxalase CH3.CHOH.COOH. 

 (methylglyoxal) > (lactic acid) 



Glyoxalgise was first isolated from dog's liver by Dakin 

 and Dudley, who showed that it converted methylglyoxal 

 quantitatively to lactic acid. Glyoxalase has also been 

 shown to be present in yeast and it has been shown that 

 L. delbrilckii and Aerobacter aerogenes convert methyl- 

 glyoxal quantitati v^ely to racemic lactic acid, whilst L. 

 delbrilckii converts hexose -diphosphate into methyl- 

 glyoxal and the latter to lactic acid. 



Some organisms, for example L. pentoaceticus , produce 

 optically inactive lactic acid, whilst others, for example 

 Str. lactis, yield the dextro-rotatory acid, and yet others, 

 for example Leuconostoc mesenter aides, the Isevo -rotatory 

 isomer. It has been shown that those organisms which 

 yield inactive lactic acid contain an enzyme, racemiase, 

 which racemises the d- or /- forms of the acid. 



The industrial production of lactic acid by fungi is 

 possible using species of Rhizopus or Mucor in surface 

 culture or in aerated submerged culture. 



