Gnaiger 2022 Abstract Bioblast-PB

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Erich Gnaiger
Went N, Di Marcello M, Gnaiger Erich (2022) Oxygen dependence of photosynthesis and light-enhanced dark respiration studied by high-resolution PhotoRespirometry.
Bioblast 2022: BEC Inaugural Conference. In:
Β»MitoFit PreprintΒ«

Link: Bioblast 2022: BEC Inaugural Conference

Went Nora, Marcello M, Gnaiger Erich (2022)

Event: Bioblast 2022

Algal biotechnology has emerged as a high-potential industry for efficient and CO2-neutral production of biomass providing biofuels, food and feed, and a variety of carbon-based chemicals and pharmaceuticals. Algal metabolism is directly involved in the regulation of growth, cell concentration, and biosynthesis of biotechnologically-relevant phytochemicals such as vitamins, antioxidants, and immune response boosters. Photoautotrophic growth rates of algae are based on light-to-chemical energy conversion and CO2 fixation, and any optimization of biomass production requires maximizing energy-use efficiency of photosynthesis and respiration, both of which vary as a function of light intensity. As such, the bioenergetic crosstalk between mitochondria and chloroplasts plays a key role in maintaining metabolic integrity and controlling intermediary metabolite production.

In the present study, we investigated how photosynthetic O2 production and respiratory O2 consumption was influenced as a function of light intensity, O2 concentration, and culture density in the unicellular model green alga Chlamydomonas reinhardtii. Cultures were grown photoautotrophically in a modified Tris-Phosphate growth medium (TRIS, N- and P-nutrient replete) at 25 Β°C, pH 7.0, and light intensity of 100 Β΅mol photonsΒ·s-1Β·m-2 (16:8 h light:dark cycle). Kinetics of light-induced O2 production and dark respiration of these microalgae was measured under culture conditions and three cell concentrations, while varying O2 concentrations in the Oroboros NextGen-O2k equipped with the PhotoBiology-Module [1] during stepwise increases of blue actinic light from from 10 to 350 Β΅molβˆ™s-1βˆ™m-2, followed by darkness, again at various controlled O2 concentrations. Maximum net photosynthesis was inhibited by 40 % at hyperoxic O2 concentrations of 550 to 650 Β΅M, when ROS production is known to be increased [2,3]. Transient light-enhanced dark respiration [4] peaked within 30 to 60 s after light-dark transitions and was 3.5- to 4-fold higher than steady-state dark respiration independent of O2 concentration in the range of 200 to 650 Β΅M.

We conclude that high-resolution photorespiratory analysis provides a new method to investigate the oxygen kinetics of O2 production and O2 consumption that reveal interactions of chloroplasts and mitochondria under precisely regulated experimental light and oxygen regimes.

  1. Went N, Di Marcello M, Gnaiger E (2021) Oxygen dependence of photosynthesis and light-enhanced dark respiration studied by High-Resolution PhotoRespirometry.
  2. KomlΓ³di T, Sobotka O, Gnaiger E (2021) Facts and artefacts on the oxygen dependence of hydrogen peroxide production using Amplex UltraRed.
  3. Shimakawa G, Kohara A, Miyake C (2020) Characterization of light-enhanced respiration in cyanobacteria.

β€’ O2k-Network Lab: AT Innsbruck Oroboros

Affiliations and support

Went N, Di Marcello M, Gnaiger Erich
Oroboros Instruments GmbH, Innsbruck, Austria
This work was part of the Oroboros NextGen-O2k project, with funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement nΒΊ 859770.

List of abbreviations, terms and definitions - MitoPedia

Β» MitoPedia: Terms and abbreviations

Labels: MiParea: Respiration, Instruments;methods, Comparative MiP;environmental MiP 

Organism: Algae 

Preparation: Intact cells 

Regulation: Oxygen kinetics  Coupling state: ROUTINE 

HRR: Oxygraph-2k, NextGen-O2k  Event: Poster  Chlamydomonas, LEDR, Photosynthesis 

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