The effects of Co~(2+)on the growth of Chlamydomonas reinhardtii and the functions of thylakoid membrane

Chlamydomonas reinhardtii (C. reinhardtii) cultures were treated with various concentrations of CoCl_2. The result demonstrated that when exposed to 0. 05 mmol/L Co~(2+) or above, the biomass and chlorophyll contents of C. reinhardtii were greatly decreased. Subsequently, the effects of CoCl_2 on the fluorescence emission spectra at room temperature, activity of DCIP photoreduction activity and polypeptide composition of thylakoid membrane from C. reinhardtii were investigated. The results demonstrated that Co~(2+) treatment (0. 5～4 mmol/L) disturbed the microenvironments of chlorophylls and amino acid residues of proteins, affecting the interactions among protein-pigment complexes of thylakoid membrane, destroyed the structural organization of thylakoid membrane at the donor side and reaction center of PSⅡ,and subsequently the photosynthetic electron transport chain was obstructed.