ORGANIC ACIDS AND OTHER PRODUCTS 



11 



have shown that this acid is produced by fermentations induced by 

 A. ochr ace ous and A. violaceiis-fuscus. Currie and Thorn (1915) 

 described a species, which they named Penicillium oxalicum, that 

 has the same ability. Indeed many mycologists have noted that a 

 wide variety of fungi, grown in nutrient agars, induce the produc- 

 tion of oxalic acid, evident as octahedral crystals of calcium 

 oxalate. 



Butkewitsch and FedororT (1930) observed that Mucor stoloni- 

 fer can convert acetates into oxalic acid, and they postulated that 

 this conversion is possible by either of these two courses: 



a. CH 3 

 COOH 



Acetic acid 



b. COOH 

 CH 3 

 CH 3 

 COOH 



Acetic acid 



• 



o 



Q 



+ o CH 2 OH _ H2 I +0 



> - — > > 



-H 2 



COOH 



Glycolic acid 



COOH 



COOH 



Glyoxalic acid 



COOH 



CH 2 

 CH 2 

 COOH 



Succinic acid 



-H 2 



COOH 



CH 

 CH 

 COOH 



Fumaric acid 



COOH 



+H 2 

 > 



COOH 

 COOH 



Oxalic acid 



COOH 

 CHOH 

 CH 2 

 COOH 



Malic acid 



-H 2 



C=0 +H2 COOH 



> 



CH, 



CH, 



COOH 



Keto- 

 succinic acid 



COOH 



Oxal- 

 acetic acid 



As another essential condition for oxalic acid production 

 Chrzaszcz and Tiukow (1930, 1930a) found that the process varies 

 with the amount and kinds of amino acids present. 



Citric acid. The production of citric acid from the fermenta- 

 tion of hexose sugars was demonstrated by Wehmer in 1893. He 

 identified the molds concerned as members of a new genus, Citro- 

 myces, and named them C. glaber and C. pfefferiammi. He found, 

 as with oxalic acid production, that improved yields can be ob- 

 tained when calcium carbonate is present in the medium. Later 



