Adenylate energy charge of a glucose-treated soil without adding a nitrogen source

Joergensen, R.G.; Raubuch, M.

Adenylate energy charge of a glucose-treated soil without adding a nitrogen source

2002

Joergensen, R.G. | Raubuch, M.

Soil microorganisms were metabolically activated by addition of glucose in one large initial ration or eight repeated additions without adding a nitrogen source. We tested whether the adenylate energy charge (AEC = (ATP + 0.5 x ADP)/(AMP + ADP + ATP) reflects this physiological activation. We compared the effects of glucose addition on adenylates with the development of microbial biomass C and biomass N from 6 h onwards during an 8 d incubation at 25 degrees C. Initial addition of 1600 microgram glucose C g(-1) soil increased microbial biomass C within 24 h from 152 to a maximum value of 469, dropping to 291 microgram g(-1) soil. In the treatment with daily addition of glucose, i.e. 8 x 200 microgram glucose C g(-1) soil, microbial biomass C increased within 24 h to roughly constant 325 mg g(-1) soil throughout the experiment. Microbial biomass N showed a smaller increase than biomass C after glucose addition, leading to increased microbial biomass C/N ratios after glucose addition, especially in the treatment with initial glucose addition. The ATP-to-microbial biomass C ratio varied in our treatments between 3.2 and 10.1 micromol g(-1) C and showed a significant negative relationship with the microbial biomass C/N ratio (r = -0.70, P < 0.0001). The average ATP-to-microbial biomass C ratios in the different treatments were 5.1 (initial glucose addition), 6.9 (daily glucose addition) and 8.9 (control) micromol g(-1). It was not possible to increase the AEC with glucose addition. The AEC was very similar in unamended and amended soils, in agreement with previous results.

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