Acidic Metabolic Products of Polyporus Sulphureus

SUMMARY

1.	Rate of acid synthesis by P. sulphureus on liquid media was investigated. On a yeast extract medium an increase of non-volatile acidity equivalent to 6 ml of normal acid per 100 ml of medium occurred during 50 days of incubation while the maximum volatile acidity which occurred on the twenty-third day was equivalent to 1.2 ml of normal acid and dropped to near zero values after the thirty-sixth day. On a chemically defined medium, maximum non-volatile acidity equivalent to 2 ml normal acid was obtained on the one hundred and twelfth day.
2.	Identification of the acidic components of the ether-soluble material from one to two liters of medium was attempted. A partition coefficient of the steam distillate of such material indicated that acetic acid was the principal volatile acid present. Crystalline precipitates from the concentrated culture medium were found to be principally oxalic acid.
3.	Fractionation of the acidic material on a silicic acid adsorption column substantiated the presence of oxalic and acetic acids and indicated that seven other acids were present in the medium. The peak effluent volumes suggested that four of these were malic, fumaric, succinic, and citric acid.

The writer is indebted to Dr. W. D. Gray for his helpful advice throughout the course of this work.