SummaryTotal lipids were extracted from the cells of Candida utilis grown at a constant population density in continuous culture. At different steady states, the environment was controlled with respect to dissolved oxygen and glucose concentrations, pH and temperature. Gas liquid chromatography was used t o follow quantitative and qualitative changes in the fatty acid composition of the cells. Increasing glucose concentration resulted in higher lipid content; high oxygen concentrations increased the level of polyunsaturated fatty acids. The most significant changes in fatty acid composition took place when both glucose and oxygen concentrations were high, and under these conditions the amount of linolenic acid was a t its highest value.

A mixture of acids, isolated from artificially grown Polyfiorus tzrwulosus Cooke, P. australiensis Wakefield, or Poria COGOS Wolf, difficult to separate, has been shown to contain a doubly unsaturated dihydroxy-monobasic acid,

No abstract

The products obtained from the transformation of (�)-piperitone (1) by Pro-actinomyces roseus, a species of Fusarium, and Aspergillus niger have been examined. Major transformation products include (�)-trans-6- hydroxy-p-menth-1-en-3-one (2) and (�)-7-hydroxy-p-menth-1-en-3-one (3); a minor transformation product has been tentatively identified as (�)-8-hydroxy-p-menth-1-en-3-one (4).

A thermodynamic feasibility study was applied as a means of predicting suitable energy-yielding substrates for growth of sulphate-reducing microorganisms. The average free energy release per electron pair for a substrate-sulphate oxidoreduction may be more or less than the energy requirement for ATP synthesis from ADP and Pi. Substrates were divided into two groups on this thermodynamic basis and the division was shown to accord with previous experimental reports; those substrates which released an average of at least 8� 4 kcal per electron pair (35�2 kJ per electron pair) were able to support growth whilst those releasing less than 8� 4 kcal were unable to do so. It is proposed that the thermodynamic assessment could be applied to a wide range of possible substrates to predict the likelihood of their serving as sole substrates for growth of these organisms.