Extraction and detection methods for polyphosphate storage in autotrophic planktonic organisms

Different extraction procedures were employed to characterise the polyphosphate granules in autotrophic planktonic organisms, the green microalgae Chlorella vulgaris and the cyanobacterium Synechocystis sp. strain PPC 6803. The effectiveness of these methods was assessed using epifluorescence microscopic analysis of DAPI stained specimens as well as by electron spectroscopic imaging. The results clearly indicate that NaOH and hot water treatment followed by filtration of the extracts are suitable to obtain a cell free suspension of intact polyphosphate granules without hydrolysing the polymers. The methods described are useful to gain physiological information on the phosphorus status of autotrophic planktonic organisms.