The relationship between natural concentrations of labile solutes and their energy content.

Calculations involving dissolved free amino acid concentrations and their energy content show interrelationships between these factors and the ability of the microbial communities to take up the labile organic substrates. Generally, the substrates having less energy per mole are found in higher concentration than those having more energy per mole. Surveying well-mixed water column systems, and less well-mixed sediment and soil systems, microdifferences are shown in areas where thorough mixing of the milieu is physically inhibited. Concentration differences, between the two systems are thought to be related to efficiencies of energy extraction under oxic compared to anoxic conditions. [ABSTRACT FROM AUTHOR]