Addition Of Sodium Pyruvate Research Articles

Pathways of Cysteine Synthesis in Aspergillus nidulans

SUMMARY: Cysteine was formed from sulphate, sulphite and thiosulphate as inorganic sulphur sources, by acetone-dried powders of Aspergillus nidulans mycelium. Added pyridoxal was obligatory for cysteine synthesis with sulphate or sulphite, and this synthesis was further enhanced by the addition of sodium pyruvate and sodium glutamate. Concomitant accumulation of cysteine sulphinic acid and utilization of glutamic acid was demonstrated. With thiosulphate, considerable synthesis of cysteine occurred in the absence of supplements, but was much enhanced by the addition of serine. Cysteine sulphinic acid did not accumulate with thiosulphate as the inorganic sulphur source. Parathiotrophic mutants, produced by ultraviolet irradiation, were used in the further elucidation of the biosynthetic mechanisms involved. Two reaction sequences: sulphate →sulphite →cysteine sulphinic acid →cysteine; and thiosulphate →cysteine-S-sulphonic acid →cysteine probably take place in the mould.

The formation of pyruvic and dimethylpyruvic acids by Aspergillus niger

Summary o 1. The formation both of pyruvic and dimethylpyruvic acids from glycerol by preformed felts of the mold Aspergillus niger , when placed on a glycerol solution containing NH 4 Cl, KH 2 PO 4 , and Na 2 SO 3 , is considerably enhanced when ethylene glycol is added to the medium, and is also enhanced, though to a less extent, by addition of glycolic acid. In neither case, however, is the increase of yield as great as are the increases produced by addition of sodium acetate to the culture fluid. 2. In similar conditions, the addition of ethanol depresses the formation of pyruvic acid but has not much effect upon that of dimethyl-pyruvic acid. 3. Addition of sodium pyruvate to the glycerol medium reduces the formation of dimethylpyruvic acid to an insignificant quantity, while sodium propionate prevents entirely the formation of both pyruvic and dimethylpyruvic acids. 4. Aspergillus niger forms pyruvic and dimethylpyruvic acids in very small yields from erythritol in Hida's medium, and addition of acetate increases somewhat the yield of both acids. 5. Formation of both keto acids from glucose in Hida's medium is not influenced by addition thereto either of sodium fluoride (0.003 M ) or of sodium iodoacetate (0.002 M ). Addition of sodium cyanide (0.02 M ) to this glucose medium reduces the yield of pyruvic acid to a trace and that of dimethylpyruvic acid to less than one-quarter of the normal yield. 6. Suggestions are made concerning the manner in which pyruvic acid and dimethylpyruvic acid may have been formed under the experimental conditions cited in this communication.