Adaptation of Divinyl Chlorophyll a/b-Containing Cyanobacterium to Different Light Conditions: Three Strains of Prochlorococcus marinus

The light-harvesting mechanisms in the three strains of Prochlorococcus marinus, CCMP1986, CCMP1375, and CCMP2773, grown under blue and red light-emitting diodes (LEDs) at two intensity levels were investigated. The blue LED was divinyl chlorophyll b (DV-Chl b) selective and the red LED was DV-Chl a selective. Under the red LED, the relative amount of DV-Chl b in CCMP1375 and CCMP2773 decreased and the relative amount of zeaxanthin increased in CCMP1375. Furthermore, the pigment composition of cells of CCMP1375 grown under red LED was remodified when they were transplanted under the blue LED. Picosecond-time-resolved fluorescence of the LED-grown Prochlorococcus was measured, and the excitation-energy-transfer efficiency between DV-Chl a did not significantly change for the different LED colors or intensities; however, a change in the pigment composition of the DV-Chl b-rich strains (CCMP1375 and CCMP2773) was observed. It appears that peripheral antenna responds to light conditions, with small modifications in the photosystems.