Figure 2.

Mass and elemental composition of T. kodakarensis cell pellets harvested from different culture media. (A) The dry masses of some cell pellets were higher than the projected mass of the total number of harvested cells (dashed lines), which was determined based on measurements of cell diameter (∅ = 1.04 or 1.24 μm) and the cell mass:volume relationship described by Lipp et al. (2008), modified from Simon and Azam (1989), suggesting that non-cellular, insoluble material was harvested in addition to cells. Specifically, harvests of the reduced-Org media and the control media at stationary phase were heavier than the predicted mass of total cells by up to 340 and 550 mg, representing a 22-fold and 5-fold excess of the projected mass of the pellet, respectively. Cells harvested from reduced-Org&P media and from control media at exponential phase were more consistent with predicted mass. (B) The reduced-Org harvests contained high amounts of non-cellular material that was rich in inorganic P relative to organic C. For this reason, these samples were excluded in further analysis of cellular P.