This communication describes the isolation of acetic acid from the mycelial felts of young cultures of citric acid-forming strains of AspergiUus niger grown on a medium of glucose and inorganic salts. The detection of pyruvic acid in cultures of A. niger on a glucose medium containing sodium arsenite is also recorded. The significance of these findings lies in the fact that various hypotheses concerning the biogenesis of citric acid assign essential roles to these two acids.Heinze (1903) reported the occurrence of acetic acid after 18 weeks in a culture of A. niger on a medium of glucose and inorganic salts, but he did not characterize it, and the literature contains no other reference to the detection of acetic acid in cultures of A. niger on glucose. Small quantities of pyruvic acid have been trapped by sodium sulphite in cultures of A. niger on sugar (Hida, 1935), but in these conditions formation of citrate is strongly depressed or inhibited, whereas in our experiments the arsenite did not depress the formation of citrate. EXPERIMENTAL METHODS AND RESULTSFornmation of acetic acid Four strains of A. niger (designated N 1, B 18, N.R.R.L. 67 and Ac. 1) were used. All, in previous work, had given citric acid in glucose media, better yields (40-50 %) having been obtained with N 1 and N.R.R.L. 67 than with the other two strains. The medium was one favourable to the formation of citric acid (Johnson, Knight & Walker, 1937). When seeking for acetic acid the glucose concentration was 17-5 % (w/v), and the pH was adjusted with HCI to 2-5 prior to inoculation. When working with strain N.R.R.L.67 the medium was that recommended by Wells, Moyer & May (1936). The temperature of incubation was 300 in all cases.The melting points given later were checked by the use of a standard thermometer, but the correction for emergent stem was not applied.Exp. 1; isolation of silver acetate. The glucose medium (5500 ml.) was divided between twenty-two conical flasks, each of 1500 ml. capacity, and inoculated with spores of strain N 1. On the fifth day, a little citric acid was present in the flasks as shown by Denig6s's (1899) (Denig6s, 1909 a, b). Another portion of the syrup yielded a reddish violet coloration on treatment with naphthoresorcinol and fuming HCI, a reaction of glyoxylic acid (Neuberg, 1910). It had been shown already that acetate yields some glycollate and glyoxylate when exposed to the action of A. niger .The mycelial felts which had been grown on the 5500 ml. of medium were washed with water, drained, ground with clean sand and extracted thoroughly, first with ether and then with hot water. The ethereal extract was evaporated and the slight residue was dissolved in the hot-water extract. This aqueous solution was then extracted continuously with ether during 50 hr. On evaporation of the ethereal extract a small quantity of liquid remained and had the smell of acetic acid. This residue was submitted to steam distillation until the liquid coming over was no longer acid, 950 ml. of distillate being collected. A 20...

Acetophenones were screened for activity against positive phototaxis of Chlamydomonas cells, a process that requires co-ordinated flagellar motility. The structure-activity relationships of a series of acetophenones are reported, including acetophenones that affect flagellar motility and cell viability. Notably, 4-methoxyacetophenone, 3,4-dimethoxyacetophenone, and 4-hydroxyacetophenone induced negative phototaxis in Chlamydomonas, suggesting interference with activity of flagellar proteins and control of flagellar dominance.

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