Adenylate energy charge in streambed sediments

Kaplan, L.A., and T.L. Bott. 1985. Freshwater Biology 15:133–138.

doi: 10.1111/j.1365-2427.1985.tb00187.x

Summary

1. The adenylate energy charge (EC_A) of microbial communities from streambed sediments was measured during three different seasons, under experimental manipulation and in culture.
2. The EC_A values of sediments (x±S.E.) in the autumn, winter and spring were low and constant; 0.22±0.03 (n=12), 0.32±0.04 (n= 12) and 0.28±0.03 (n=6) respectively.
3. A 5 h exposure of sediments to an algal lysate at 3.0–4.0°C and a 48 h exposure of sediments to tryptone-yeast extract at 8.0–18.0°C failed to increase EC_A even though respiration increased 3.7-fold during the latter exposure.
4. The cellular EC_A of a bacterial monoculture, sampled in log phase, was 0.90±0.10 (n=3), but extracellular AMP depressed the total culture EC_A to 0.21±0.01 (n=4).
5. Attempts to isolate extracellular AMP from the interstitial waters of sediments were unsuccessful.
6. The data suggest that under natural conditions EC_A is of limited use as a monitor of subtle changes in the physiological state of microbial communities in streambed sediments.