Abstract
Low‐temperature (77°K) fluorescence and absorption spectra have been determined for whole cells and photosystem I particles of Anacystis nidulans grown in iron‐supplied or iron‐deficient inorganic media. Iron deficiency induces a decrease of F720 relative to F685 and F695 in the fluorescence spectra of both whole cells and photosystem I particles. This change is correlated to a reduction of preferentially the long wavelength absorbing fraction of chlorophyll a. The relative fluorescence intensity at 755 nm is increased by iron deficiency. No significant effects of culture‐age are found in the ratio between the three fluorescence bands (F685: F695: F720) of iron‐supplied A. nidulans.