A new type of adaptation of the cyanobacterium Spirulina platensis to illumination conditions

摘要

Incubation of cells of the cyanobacterium Spirulina platensis under conditions of exposure to low-intensity (2-3 mu E m~(-2) s~(-1)) red light, which was predominantly absorbed by photosystem I (PS I), caused atypical adaptation changes. Invariable pigment composition and stoichiometry of photosystems was observed in the cells incubated under these conditions against the background of a decrease in the rate of photosynthetic fixation of CO_2 (by one-half) and a 1.5-fold increase in the rate of darkrespiration relative to cells incubated under conditions of exposure to green light. Comparison of these data with a high rate of dark relaxation of P700~+ in the presence of diuron suggests that deficiency of reduced equivalents at the donor side of PSI in the Spirulina cells exposed to red light is compensated by electron supply from the respiratory chain NAD(P)H dehydrogenase complex.