Open AccessElectrochemical and mass spectrometric investigations on the light‐induced oxygen and hydrogen gas exchange in cyanobacteria
Author(s) -
Bader Klaus P.
Publication year - 1996
Publication title -
berichte der bunsengesellschaft für physikalische chemie
Language(s) - English
Resource type - Journals
ISSN - 0005-9021
DOI - 10.1002/bbpc.19961001213
Subject(s) - oxygen evolution , oxygen , cyanobacteria , hydrogen , chemistry , light intensity , chemical physics , amplitude , nitrogen , photochemistry , analytical chemistry (journal) , electrochemistry , physics , electrode , environmental chemistry , biology , optics , bacteria , organic chemistry , genetics
The filamentous cyanobacterium Oscillatoria chalybea evolves molecular hydrogen upon illumination with one or more short (5 μs) saturating light flashes. This hydrogen evolution appears not to be linked to the nitrogen fixation capacity of this organism as the amplitudes are identical with nitrate‐grown and nitrogen free‐grown cultures. The hydrogen evolution amplitudes remain virtually constant over the whole series of flashes, i.e. no oscillatory pattern is observed. The dependence of the oxygen evolution signal under the third flash of a sequence on the light intensity shows significant differences, if the relative intensities of the first, second or third flash are modulated. In view of current discussions this might be interpreted in terms of a charge transfer between reaction centers and thus of a limited independence of the centers—as it has been suggested for e.g. Synechococcus . Addition of quaternary ammonium salts like alkylbenzyldimethyl ammoniumchloride (ABDAC; zephirol) strongly increases the oscillation of the oxygen evolution patterns but does not induce a (period‐2) oscillation in the case of hydrogen evolution. Our results suggest that also in the case of cyanobacteria ( Oscillatoria chalybea ) the reaction centers act independently so that the strong damping of the oscillation of the oxygen evolving amplitudes must be explained in terms of the ‘missed’ transitions between the sequential oxidation steps.