This 1977 study examined adenylate energy charge (a measure of cellular energy status calculated from ATP, ADP, and AMP levels) in the rapidly-growing marine bacterium Beneckea natriegens during batch culture. Researchers used rapid sampling techniques (spring-loaded syringes with quick quenching in perchloric acid) to accurately capture adenine nucleotide levels. During exponential growth on succinate or glucose, the intracellular ATP content remained constant at 5-8 nmol per mg dry bacterial weight, and energy charge stayed approximately constant at 0.9. Total ATP in cultures increased proportionally with growth. When growth ceased due to carbon or nitrogen depletion, significant ATP fluctuations occurred depending on substrate availability. Addition of cyclic AMP (2 mM) to glucose-limited cultures reduced acid production and increased ATP levels during non-growth phases but maintained constant energy charge during growth. The findings demonstrate that adenylate energy charge remains remarkably stable as a regulatory parameter during active growth across different nutrient limitation scenarios, though absolute ATP pools vary based on growth phase and nutrient conditions.

Key findings

• Adenylate energy charge remained constant at ~0.9 during exponential growth and early stationary phase, despite high ATP turnover rates in this rapidly-dividing bacterium
• Intracellular ATP content stayed constant during exponential growth (5-8 nmol/mg dry weight) while total culture ATP increased proportionally with biomass
• ATP content fluctuated significantly upon growth cessation and varied based on whether growth terminated from carbon or nitrogen limitation
• Added cyclic AMP (2 mM) reduced organic acid production and elevated ATP levels during non-growth phases without altering energy charge stability during growth
• Rapid sampling and immediate quenching with perchloric acid proved essential for accurate adenine nucleotide measurements in this fast-growing organism