EVIDENCE FOR AN ULTRAVIOLET SUNSCREEN ROLE OF THE EXTRACELLULAR PIGMENT SCYTONEMIN IN THE TERRESTRIAL CYANOBACTERIUM Chiorogloeopsis sp.

Ferran Garcia‐Pichel, Nelson D. Sherry, Richard W. Castenholz

Research output: Contribution to journalArticle

239 Scopus citations

Abstract

Abstract— The proposed photoprotective role of the UV‐A absorbing, extracellular pigment scytonemin was studied in the terrestrial cyanobacterium Chlorogloeopsis sp. strain O‐89‐Cgs(1). UV‐A (315–400 nm) caused growth delay, cell growth restarting only when scytonemin had accumulated in the extracellular envelopes. Cultures with scytonemin were more resistant to photoinhibition of photosynthesis than cultures without scytonemin, the differential resistance being much greater to UV‐A‐caused photoinhibition than to photoinhibition caused by visible light. The presence of scytonemin in the extracellular envelopes was correlated with the inability of UV‐A radiation to induce strong photopigment fluorescence (685 nm emission), regardless of the specific content os photosynthetic pigments. The physical removal of the scytonemin containing extracellular envelopes brought about the loss of UV‐A resistance as measured by photobleaching rates of chlorophyll a under conditions of physiological inactivity (desiccation). These observations provide strong evidence for the proposed protective role of scytonemin, as a passive UV‐A sunscreen, in cyanobacteria.

Original languageEnglish (US)
Pages (from-to)17-23
Number of pages7
JournalPhotochemistry and photobiology
Volume56
Issue number1
DOIs
StatePublished - Jul 1992
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Physical and Theoretical Chemistry

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