Specific Features of Technogenic Pollutants Impact on Photosynthetic Activity of Unicellular Cyanobacteria

The effect of heavy-metal ions (Cd2+, Cr6+, and Cu2+) on cyanobacteria sp. Microcystis and sp. Synechocystis has been studied. Since heavy metals impact causes blocking of light-energy transmission channels and arrest of electron transport in photosynthetic apparatus of cyanobacteria, their influence can be detected within a few hours by fluorescence techniques. In this investigation three standard fluorescence techniques are used: fluorescence spectroscopy, pulsed amplitude modulation fluorimetry, and confocal microscopic spectroscopy. All three used methods showed a decrease in photosynthetic activity for cyanobacterial cells exposed to heavy metals. However, the mechanisms of action for different heavy metals are slightly different. In this paper, we analyze variations in spectroscopic and kinetic properties of emmitted fluorescence for cyanobacterial cultures and single living cells in order to identify a specific mechanism of heavy metals influence.