Selection and characterization of transposon tagging mutants of<Emphasis Type="Italic">Synechocystis</Emphasis> sp. PCC 6803 sensitive to high-light and oxidative Stresses

We compared several analytical tools to identify which were most applicable for the selection and characterization of specific transposon-tagged mutant strains ofSynechocystis sp. PCC 6803 that are sensitive to high light and oxidative stresses. Our primary parameter was the maximum photochemical efficiency of dark-adapted cells, a very sensitive factor that can be determined in a non-destructive manner. Using this as a tool for primary selection, we identified five mutant strains with different sensitivities to photoinhibition and photooxidation. For further characterization, we obtained data describing the absorption spectra for pigment contents, the 77K fluorescence spectra, non-photochemical quenching (as a down-regulation process), and the photosynthetic electron transfer rate. Based on these results, we were able to design a strategy for selecting mutants with specific phenotypes. Here, we also discuss the strengths and weaknesses of each selection and characterization tool.