Table 1.

Oxygen isotope compositions of water and dissolved inorganic PO₄ derived from various P sources and metabolized by microbial cell cultures at 25°C and plotted in Fig. 1

P source	δ18Ow	δ18Op
5 mM Pi	99	82.6
10 mM Pi	−17.7	7.3
	−6.0	18.0
	12.6	35.6
RNA	−6.1	13.0
	−6.5	12.8
	−19.3	3.6
	−8.0	11.1
	10.4	21.7
Glucose-1-PO4	−18.2	4.1
	−6.7	12.1
	42.2	57.9