High Temperature Stress Induced Alterations in the Energy Transfer Process of Photosystem II in the Spheroplasts of Synechococcus 6301

Exposure of Synechococcus spheroplasts to high temperature caused the changes in both absorption and fluorescence emission properties of phycobiliproteins. High temperature stress caused the decrease in phycocyanin absorption at 622 nm and increase in the fluorescence intensity by 50%. In addition it induced a red shift in the peak position. This red shift indicated the alterations in the energy transfer with in the phycobilisomes. Fluorescence excitation spectra also supported the above proportion by showing large increase at 667 nm in excitation spectra.