The measurement and significance of ATP pools in filamentous blue-green algae

Abstract

A modified luciferin-luciferase assay has been developed for measuring ATP pools in filamentous blue-green algae. The assay, which should be applicable to studies on algae in general, is simple, reliable, inexpensive, sensitive at the pmole level and can be used in any laboratory with a suitable liquid scintillation counter. Studies using the two blue-green algae, Anabaena cylindrica and Anabaenopsis circularis (strain 6720) show that in steady state cultures, good correlations exist between the size of the extractable ATP pool and algal biomass measured on the basis of cellular dry weight, chlorophyll, total nitrogen and total carbon. This correlation holds at measured ATP levels up to 2400 pmoles of ATP extracted or up to 400 pmoles per ml of culture. At higher densities of algae the relationship is non-linear. The size of the extractable ATP pool of A. cylindrica and A. circularis is usually in the range of 150–200 nmoles ATP mg chl a -1 which represents approximately 0·20–0·25% of the total cellular carbon. There is evidence of a rapid turnover of ATP molecules in blue-green algae in the light and dark and that the algae show a remarkable capacity to maintain their ATP pool. However certain changes in environmental or metabolic conditions can result in rapid changes in the ATP pool which are not manifested by corresponding rapid changes in algal biomass. The findings are discussed in relation to the use of ATP analysis in physiological and ecological studies on blue-green algae.