SUMMARY

Alcohols, amino acids, organic acids and sugars were tested as carbon sources for the growth of Pyrobotrys (Chlamydobotrys) stellata in the light and dark. Growth was only recorded with acetate in the light. A carbon balance sheet of 14C-acetate assimilation showed a greater incorporation of 14C into polysaccharide and less released as 14C02 in the light, compared with the dark. The primary products of 14C-acetate assimilation into the soluble fraction of the organisms were identified; after 10 sec. 40 % of the total 14C present in this fraction was in succinic acid, 15 % in citric acid and 16 % in malic acid. The percentage of total 14C in this fraction present in succinic and malic acids decreased consistently with time, while that in citric acid initially increased before decreasing. After 10 sec. the specific activity of succinic acid was more than twice that of citric acid. 4 x M-monofluoroacetate (MFA) effectively inhibited the incorporation of 14C-acetate into tricarboxylic acid cycle intermediates and. related compounds, and markedly inhibited l4COZ evolution. ~-N1-(3-4,dichlorophenyl)-N,N-dimethyl urea (DCMU) did not significantly inhibit 14C-metabolism. The key enzymes of the glyoxylate cycle, isocitrate lyase (E. C. 4.1.3.1) and malate synthetase (E. C. 4.1.3.2) were found to be present in P. stellata, and did not disappear in the absence of acetate, but even so growth was not recorded on acetate in the dark