Dataset: Cell abundance, nutrient concentrations, and intracellular phosphorus pools in Synechococcus sp. WH8102 continuous (EFB) culture experiments

Synechococcus sp. WH8102 was grown in exponentially fed batch (EFB) continuous cultures under controlled laboratory conditions to maintain near steady-state physiology. Cultures were maintained at 26 °C on a 12:12 h light:dark cycle (250 µE m⁻² s⁻¹) in SN medium with three phosphorus treatments: High-P (36 µM), Mid-P (5 µM), and Low-P (1 µM). Continuous dilution rates were adjusted (0.35, 0.25, and 0.12 d⁻¹, respectively) to match growth rates and maintain stable biomass.

Samples were collected daily and processed immediately. Cell abundance was measured using a Coulter Counter, and growth rates were calculated from changes in in vivo fluorescence (measured by fluorometry), corrected for dilution. Subsamples were filtered onto 0.2 µm polycarbonate or GF/F filters for intracellular phosphorus analyses and stored at −80 °C or extracted immediately, depending on the assay.

Intracellular phosphorus pools were quantified across major macromolecular fractions, including ATP, DNA, RNA, phospholipids, and polyphosphate, using established biochemical and fluorometric methods. ATP was measured via bioluminescence, nucleic acids via fluorometric assays, polyphosphate via dye-based fluorometry, and phospholipid-associated P following extraction and colorimetric phosphate determination. Dissolved and particulate phosphorus fractions, including soluble reactive phosphorus (SRP), total particulate phosphorus (TPP), and intracellular inorganic phosphate (Pi), were measured using standard colorimetric methods. Intracellular phosphorus pools, including ATP, DNA, RNA, phospholipid-associated phosphorus (P_lipid), free inorganic phosphate (free_Pi), and polyphosphate (PolyP), as well as TPP, are reported as bulk concentrations in the culture (µM), phosphorus quotas per cell (fmol cell⁻¹), and phosphorus normalized to cell biovolume (fmol µm⁻³).

Together, these approaches enabled quantification of cellular phosphorus allocation and nutrient dynamics under controlled phosphorus supply conditions.