Photoassimilation of Acetate by Algae

Acetate concentrations in organic-rich anaerobic surface sediments may reach 300 ++M with associated high flux into the water column, and fall within the range of reported half-saturation constants for acetate uptake by algae (about 1 mM; cf. Reference ). In addition, it has been reported that [C]-acetate stocks are often contaminated with [C]-carbonate, which can be assimilated by algae in the light. To minimize the effects of containment-induced bacterial growth, acetate photoassimilation studies should be kept to as short an incubation as possible. In pure cultures of algae, the proportion of [C]-acetate respired to CO₂ can be much greater in the dark than in the light, whereas this difference is expected to be negligible for bacterial metabolism. To simplify calculations to integer format it is convenient to work at the dpm L level, since less than 1% of the label is often taken up under the incubation conditions described, and that amount is further divided among the subcellular fractions.