Hydrogen Photoevolution Indicates an Increase in the Antenna Size of Photosystem I in Chlamydobotrys stellata during Transition from Autotrophic to Photoheterotrophic Nutrition

Abstract

The changes in the light-harvesting antenna size of photosystem I were investigated in the green alga Chiamydobotrys stellata during transition from autotrophic to photoheterotrophic nutrition by measuring the light-saturation behavior of hydrogen evolution following single turnover flashes. It was found that during autotrophic-to-photoheterotrophic transition the antenna size of photosystem I increased from 180 to 250 chlorophyll. The chlorophyll (a + b)/P700 ratio decreased from 800 to 550. The electron transport of photosystem I measured from reduced 2,6-dichlorophenolindophenol to methylviologen was accelerated 1.4 times. In the 77K fluorescence spectra, the photosystem II fluorescence yield was considerably lowered relative to the photosystem I fluorescence yield. It is suggested that the increased light-harvesting capacity and redistribution of absorbed excitation energy in favor of photosystem I is a response of photoheterotrophic algae to meet the ATP demand for acetate metabolism by efficient photosystenr. I cyclic electron transport when the noncyclic photophosphorylation is inhibited by CO2 deficiency.In the green alga Chlamydobotrys stellata, the ultrastructure and photosynthetic activities of chloroplast membranes depend on the nutritional conditions. Autotrophically grown cells evolve oxygen and utilize CO2 as a carbon source, like other unicellular green algae (25). Under heterotrophic culture conditions when CO2 is replaced by acetate, 02 evolution is abolished and only PSI activity is necessary for acetate metabolism (26,27). In the photoheterophic cells, the membrane structure of the chloroplasts is almost grana free (28) and the amount of

Local bioprospecting for high-lipid producing microalgal strains to be grown on concentrated municipal wastewater for biofuel production

“…It is clear that the biomass productivity found in this study ranked among the top ones in terms of total suspended solid concentration. There are reported evidences indicating that some heterotrophic algae utilize organic carbons more efficiently under light condition than in dark (McKinley and Wetzel, 1979;Boichenko et al, 1992). Furthermore, it was suggested that the growth rate for algae grown in mixotrophic way was almost the sum of autotrophic and heterotrophic growth (Lee, 2007).…”

Hydrogen evolution in relation to PS I-reducible substrates in the cyanobacterium Oscillatoria chalybea assayed by means of mass spectrometry

“…In Chlamydomonas stellata, the antenna size of PS I might increase during transition from autotrophic nutrition to hydrogen evolution [21]. Therefore, a number of oxidized substrates, also known to be reducible by PS I, were applied seeking their probable competition with protons on photosynthetic electrons in the cyanobacterium O. chalybea.…”

Simultaneous increases in specific growth rate and specific lipid content of Chlorella vulgaris through UV‐induced reactive species

“…The PSI content of cells was determined by the redox difference spectrum according to the method of Boichenko et al, using a differential excitation coefficient, ε = 64 mM −1 cm −1 at 700 nm . The PSII content was calculated as one half molar of the Cyt b 559 content of the cell, determined by the redox difference spectrum as previously described .…”