Molecular Response of the Bloom-Forming Cyanobacterium, Microcystis aeruginosa, to Phosphorus Limitation

摘要: Cyanobacteria blooms caused by species such as Microcystis have become commonplace in many freshwater ecosystems. Although phosphorus (P) typically limits the growth of phytoplankton populations, little is known regarding molecular response to variation P concentrations and sources. For this study, we examined genes involved acquisition including two high-affinity phosphate-binding proteins (pstS sphX) a putative alkaline phosphatase (phoX). Sequence analyses among ten clones aeruginosa one clone wesenbergii indicates that these are present conserved within species, but perhaps not genus, phoX was identified M. wesenbergii. Experiments with indicated expression three strongly upregulated (50- 400-fold) under low inorganic conditions correlated activity (p < 0.005). In contrast, cultures grown exclusively on high levels organic sources (adenosine 5′-monophosphate, β-glycerol phosphate, d-glucose-6-phosphate) or nitrogen-limited displayed neither gene nor activity. Since dominates assemblages summer when (Pi) often and/or dominate lakes Pi P, our findings suggest cyanobacterium may rely pstS, sphX, efficiently transport exploit form blooms.