Effects of Oxygen Limitation on the Biosynthesis of Photo Pigments in the Red Microalgae Galdieria sulphuraria Strain 074G

Sarian, Fean Davisunjaya; Rahman, Delicia Yunita; Schepers, Otto; Maarel, Marc J. E. C. van der

doi:10.1371/journal.pone.0148358

Cited by 10 publications

(4 citation statements)

References 27 publications

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“…The residual presence of oxygen might have been enough to interfere with the oxygen‐sensitive [4Fe‐4S] cluster of the enzyme or perhaps prevent its activation. This result is line with the study of Sarian et al (2016). In that work, G. sulphuraria was cultivated mixotrophically without aeration and the oxygen remained at 0% air saturation for days.…”

Section: Resultssupporting

confidence: 94%

“…We monitored anoxic stress in the cultures by indirectly measuring the accumulation of COPROIII in the supernatant, displayed in Figure 3. This molecule has been previously identified as a marker of anoxia in G. sulphuraria (Sarian et al, 2016;Zhu et al, 2022). Because it is released to the supernatant and has a characteristic pink color, it can be easily detected by measuring absorbance with a spectrophotometer at 400 nm.…”

Section: Coproiii Accumulated In the Mediummentioning

confidence: 99%

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Scale‐down of oxygen and glucose fluctuations in a tubular photobioreactor operated under oxygen‐balanced mixotrophy

Fernández

García

Jansen

et al. 2023

Biotech & Bioengineering

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Oxygen-balanced mixotrophy (OBM) is a novel type of microalgal cultivation that improves autotrophic productivity while reducing aeration costs and achieving high biomass yields on substrate. The scale-up of this process is not straightforward, as nonideal mixing in large photobioreactors might have unwanted effects in cell physiology. We simulated at lab scale dissolved oxygen and glucose fluctuations in a tubular photobioreactor operated under OBM where glucose is injected at the beginning of the tubular section. We ran repeated batch experiments with the strain Galdieria sulphuraria ACUF 064 under glucose pulse feeding of different lengths, representing different retention times: 112, 71, and 21 min. During the long and medium tube retention time simulations, dissolved oxygen was depleted 15-25 min after every glucose pulse. These periods of oxygen limitation resulted in the accumulation of coproporphyrin III in the supernatant, an indication of disruption in the chlorophyll synthesis pathway. Accordingly, the absorption cross-section of the cultures decreased steeply, going from values of 150-180 m 2 kg −1 at the end of the first batch down to 50-70 m 2 kg −1 in the last batches of both conditions. In the short tube retention time simulation, dissolved oxygen always stayed above 10% air saturation and no pigment reduction nor coproporphyrin III accumulation were observed. Concerning glucose utilization efficiency, glucose pulse feeding caused a reduction of biomass yield on substrate in the range of 4%-22% compared to the maximum levels previously obtained with continuous glucose feeding (0.9 C-g C-g −1 ).The missing carbon was excreted to the supernatant as extracellular polymeric substances constituted by carbohydrates and proteins. Overall, the results point out the importance of studying large-scale conditions in a controlled environment and the need for a highly controlled glucose feeding strategy in the scale-up of mixotrophic cultivation.

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Section: Resultssupporting

confidence: 94%

Section: Coproiii Accumulated In the Mediummentioning

confidence: 99%

Scale‐down of oxygen and glucose fluctuations in a tubular photobioreactor operated under oxygen‐balanced mixotrophy

Fernández

García

Jansen

et al. 2023

Biotech & Bioengineering

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“…However, excess glucose and light supply inhibited the photopigments’ biosynthesis, attributed to the inactivation of the oxygen-dependent coproporphyrinogen III oxidase. This enzyme converts coproporphyrinogen III to protoporphyrinogen IX, a critical step in chlorophyll and phycobilin biosynthesis [ 37 ]. Thus, the observed decrease in photopigments chlorophyll and phycobilin is most likely due to the limited oxygen for the oxygen-dependent oxidoreductase.…”

Section: Discussionmentioning

confidence: 99%

Untargeted Metabolomics Unveil Changes in Autotrophic and Mixotrophic Galdieria sulphuraria Exposed to High-Light Intensity

Liu

Sanchez-Arcos

Pohnert

et al. 2021

IJMS

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The thermoacidophilic red alga Galdieria sulphuraria has been optimizing a photosynthetic system for low-light conditions over billions of years, thriving in hot and acidic endolithic habitats. The growth of G. sulphuraria in the laboratory is very much dependent on light and substrate supply. Here, higher cell densities in G. sulphuraria under high-light conditions were obtained, although reductions in photosynthetic pigments were observed, which indicated this alga might be able to relieve the effects caused by photoinhibition. We further describe an extensive untargeted metabolomics study to reveal metabolic changes in autotrophic and mixotrophic G. sulphuraria grown under high and low light intensities. The up-modulation of bilayer lipids, that help generate better-ordered lipid domains (e.g., ergosterol) and keep optimal membrane thickness and fluidity, were observed under high-light exposure. Moreover, high-light conditions induced changes in amino acids, amines, and amide metabolism. Compared with the autotrophic algae, higher accumulations of osmoprotectant sugars and sugar alcohols were recorded in the mixotrophic G. sulphuraria. This response can be interpreted as a measure to cope with stress due to the high concentration of organic carbon sources. Our results indicate how G. sulphuraria can modulate its metabolome to maintain energetic balance and minimize harmful effects under changing environments.

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“…The red microalga Galdieria partita, also containing both forms of CPO, excretes Copro in the medium when growing mixotrophically on glucose (35). This was explained by inactivation of the oxygen-dependent CPO in microoxic conditions when grown on glucose (36). In Synechocystis 6803, the twocomponent regulatory histidine kinase Hik31 is involved in the response to glucose and in switching between photoautotrophic and photoheterotrophic growth (37).…”

Section: Discussionmentioning

confidence: 99%

The cyanobacterial protoporphyrinogen oxidase HemJ is a new b-type heme protein functionally coupled with coproporphyrinogen III oxidase

Skotnicová

Sobotka

Shepherd

et al. 2018

Journal of Biological Chemistry

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Effects of Oxygen Limitation on the Biosynthesis of Photo Pigments in the Red Microalgae Galdieria sulphuraria Strain 074G

Cited by 10 publications

References 27 publications

Scale‐down of oxygen and glucose fluctuations in a tubular photobioreactor operated under oxygen‐balanced mixotrophy

Scale‐down of oxygen and glucose fluctuations in a tubular photobioreactor operated under oxygen‐balanced mixotrophy

Untargeted Metabolomics Unveil Changes in Autotrophic and Mixotrophic Galdieria sulphuraria Exposed to High-Light Intensity

The cyanobacterial protoporphyrinogen oxidase HemJ is a new b-type heme protein functionally coupled with coproporphyrinogen III oxidase

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