The Production of Pyruvic and {alpha}-Oxoglutaric Acids by Mucor Species

Six out of the seven species of Mucor studied (M. plumbeus,M. racemosus, M. rouxii, M. hiemalis, M. ramannianus, and M.mucedo) are shown to produce pyruvic acid when grown on a mediumcontaining glucose, glutamate, and mineral salts. Mucor pusillusproduces no detectable pyruvate on this medium. The proportionof the carbohydrate metabolized which is excreted as pyruvateis greatest in species having a high thiamine requirement forgrowth. Addition of thiamine to the culture medium reduces pyruvateexcretion. However, in the species which need added thiaminefor growth, the growth requirement is almost completely satisfiedby 20 µg thiamine per litre whereas suppression of pyruvateexcretion requires about 200 µg thiamine per litre. Experimentswith M. plumbeus show that the yield of pyruvate is reducedwhen xylose is substituted for glucose and also when alanineis substituted for glutamate in the medium. -Oxoglutaric acidis produced by all seven species on the glucose/glutamate medium,the yield varying with the species. This acid is partly derivedfrom the glutamate in the medium.