A complex photoreceptive structure in the cyanobacterium Leptolyngbya sp.

Among the terrestrial epilithic cyanobacteria isolated from Roman hypogea a t extremely low light intensity, a non-heterocystous strain, belonging to t he genus Leptolyngbya, showed a marked photobehavior. These red cyanobacter ia possess an orange spot at the tip of the apical cell. Micro-spectrophoto metric analysis of this tip showed an absorption spectrum with two bands, c entered at 456 and 504 nm, respectively. Experiments on photo-orientation i mpairment of these cells, and micro-spectrophotometric analysis of the tip of impaired trichomes showed that a rhodopsin-like protein might be present in this structure. All these data could support the hypothesis of the pres ence of a complex photoreceptive system in this prokaryote. (C) 1999 Elsevi er Science Ltd. All rights reserved.