Intracellular phosphorus metabolism of Microcystis aeruginosa under various redox potential in darkness.

Phosphorus metabolism of Microcystis aeruginosa was studied under gradient redox potential from 252 mV to -70 mV in darkness. The release of phosphorus occurred in all the treatments, and this process was accelerated in darkness when the redox potential was lowered. Low redox potential in darkness stimulated the accumulation of polyphosphate (PolyP) and the degradation of polyglucose. The synthesis of PolyP delayed the decrease of intracellular orthophosphate. The death of M. aeruginosa was slowered when the redox potential was low in darkness. The accumulation of PolyP under low redox potential in the dark was very important to M. aeruginosa for endurance through the unfavorable growth conditions for maintaining phosphorus concentration, energy storage, and other physiological functions. The ability to accumulate PolyP in the dark and negative redox potential may be of considerable advantage in the low-light, organically rich, and low-redox habitats.