Fluorescence properties of the chlorophyll d-dominated cyanobacterium Acaryochloris sp. strain Awaji

Abstract Fluorescence properties of the newly discovered chlorophyll (Chl) d -dominated cyanobacterium, Acaryochloris sp. strain Awaji were examined by a combination of steady state and the time-resolved fluorescence measurements. Acaryochloris sp. strain Awaji, in contrast to Acaryochloris marina MBIC11017, exhibited photosystem (PS) II fluorescence at 745 nm at room temperature and at 750 nm at −196 °C with a few Chl d components in the shorter wavelength region of the maxima. PS I fluorescence was not detected by steady state measurements but was by time-resolved spectroscopy as a transient component. The results clearly indicated diversity in the antenna systems in the genus Acaryochloris that contains Chl d as major pigments. Delayed fluorescence was observed only in the Chl a fluorescence region, consistent with A. marina . This strongly suggested that the primary electron donor for the PS II reaction center should be Chl a , which is identical to all other oxygenic photosynthetic organisms.