Adenosine triphosphate (ATP) and deoxyribonucleic acid (DNA) content of marine microalgae and bacteria with applications for measuring marine microbial growth rates and production

Laboratory experiments investigated DNA:ATP ratios in marine bacteria and microalgae, which were used to estimate living microbial DNA concentrations in the open ocean. These estimates, and measurements of microbial DNA synthesis rates, allowed calculation of microbial specific growth rates. The relationship between microbial DNA and carbon was used to estimate total microbial (defined as phytoplankton + bacterial) production.;DNA:ATP ratios ranged from 8.5-33 (wt:wt) for cultured marine microalgae, and from 13-50 for exponentially growing marine bacteria, with an overall geometric mean ratio of 17. C:DNA ratios ranged from 33-176 (wt:wt) for marine algae, and from 17-51 for marine bacteria, with an overall geometric mean of 49. There were no statistically significant diel differences in DNA:ATP ratios for the marine algae studied. Significantly different DNA:ATP ratios were observed between high and low growth rates and between N- and P-limited cultures for some species. Calibration experiments with marine algae confirmed that observed DNA:ATP ratios and measured DNA synthesis rates could yield good growth rate estimates.;Total microbial growth rates and production were measured during spring and fall, 1986, at 26;It is concluded that microbial growth rates can be accurately estimated by the techniques used. Microbial communities in the study area were growing rapidly, at approximately one doubling per day. Accuracy of total microbial production estimates would be improved by information concerning the partitioning of particulate ATP among members of the microbial community, and by knowledge of the turnover time of grazed microbial DNA.