Adenosine triphosphate ( <scp>ATP</scp> ) as a metric of microbial biomass in aquatic systems: new simplified protocols, laboratory validation, and a reflection on data from the literature

The use of adenosine triphosphate (ATP) as a universal biomass indicator is built on the premise that ATP concentration tracks rather than physiological condition cells. However, reportedly high variability in response to environmental conditions main reason method has not found widespread application. To test possible sources this variability, we used diatom Thalassiosira weissflogii model and manipulated its growth rate through nutrient limitation exposure three different temperatures (15°C, 20°C, 25°C). We simplified protocol with hot-water or chemical extraction methods, modified commercially available luciferin-luciferase assay, employed single-photon counting scintillation counter, all which increased sensitivity throughput. Per-cell levels remained relatively constant despite changes rates by approximately 10-fold batch culture (i.e., limitation) experiments, 2-fold temperature. re-examination related literature values revealed average cellular differed little among taxonomic groups aquatic microbes, even at domain level, correlated well bulk properties such elemental carbon nitrogen. Fulfilling multiple functions addition being energy currency requires be maintained millimolar range. Consequently, relates directly live cytoplasm volume, while nitrogen are constrained an indeterminate pool detrital material intracellular storage compounds. ATP-biomass sensitive, economical, can readily standardized laboratories across environments.