0000000001176492
AUTHOR
Gilles Curien
The Water to Water Cycles in Microalgae.
In oxygenic photosynthesis, light produces ATP plus NADPH via linear electron transfer, i.e. the in-series activity of the two photosystems: PSI and PSII. This process, however, is thought not to be sufficient to provide enough ATP per NADPH for carbon assimilation in the Calvin-Benson-Bassham cycle. Thus, it is assumed that additional ATP can be generated by alternative electron pathways. These circuits produce an electrochemical proton gradient without NADPH synthesis, and, although they often represent a small proportion of the linear electron flow, they could have a huge importance in optimizing CO2 assimilation. In Viridiplantae, there is a consensus that alternative electron flow comp…
Supplementary Fig. 4 A Respiration and photosynthesis in P. tricornutum cells from Investigating mixotrophic metabolism in the model diatom Phaeodactylum tricornutum.
Direct assessment of oxygen consumption by a polarographic approach in both phototrophy (black bar) and mix-otrophy (red bar). B. Fluorescent based-assay to monitoring the changes in respiration using the Redox Dye A in presence of the selected compounds (see methods).
Supplementary Fig. 1 Quantitative analysis of P. tricornutum glycerolipids from Investigating mixotrophic metabolism in the model diatom Phaeodactylum tricornutum.
TAG profile in a total lipid extract from cells grown in replete conditions (A) and deplete conditions (B) in both mixotrophic and phototrophic mode. Glycerolipids are expressed in nmol / mg of dry cells. Each result is the average of two biological replicates ± SD. PHOT: light in N-replete condition; PHOTO-N: light in N-deplete condi-tion; MIX: light+glycerol in N-replete condition; MIX-N: light+glycerol in N-deplete condition.
Supplementary Fig. 2 Membrane lipid composition in P. tricornutum from Investigating mixotrophic metabolism in the model diatom Phaeodactylum tricornutum.
Lipid analysis of cells grow in N-replete conditions and N-deplete conditions in both mixotrophic and phototrophic mode. Each result is the average of two biological replicates ± SD. SQDG, sulfoquinovosyldiacylglycerol; DGDG, digalactosyldiacylglycerol; MGDG, monogalactosyldiacylglycerol; PC, phosphatidylcholine; PHOT: light in N-replete condition; PHOTO-N: light in N-deplete condition; MIX: light+glycerol in N-replete condition; MIX-N: light+glycerol in N-deplete condition.
Investigating mixotrophic metabolism in the model diatom Phaeodactylum tricornutum.
Diatoms are prominent marine microalgae, interesting not only from an ecological point of view, but also for their possible use in biotechnology applications. They can be cultivated in phototrophic conditions, using sunlight as the sole energy source. Some diatoms, however, can also grow in a mixotrophic mode, wherein both light and external reduced carbon contribute to biomass accumulation. In this study, we investigated the consequences of mixotrophy on the growth and metabolism of the pennate diatom Phaeodactylum tricornutum , using glycerol as the source of reduced carbon. Transcriptomics, metabolomics, metabolic modelling and physiological data combine to indicate that glycerol affect…
Supplementary Fig. 3 Quantification of intracellular pyruvate by a fluorescence-based method from Investigating mixotrophic metabolism in the model diatom Phaeodactylum tricornutum
A. Pyruvate standard curve. B. Quantification of intracellular pyruvate in cells grown in phototrophy (PHOT) and mixotrophy (MIX).
Supplementary Fig. 5 Screening of mixotrophic efficiency by biolog and redox dye assay in P. tricornutum from Investigating mixotrophic metabolism in the model diatom Phaeodactylum tricornutum.
A. OD750 nm changes (relative to phototrophic growth) of P. tricornutum cells grown for 6 days in BiologTM plates P1 and PM2A that contains 190 carbon compounds (see methods). Each data point represents a different com-pound. B. Growth profile of P. tricornutum on few selected compounds (at 20 mM) and a phototrophic control in 100 mL flasks. C. Areas under the growth curves of Supplementary Fig. 5B normalized to the area of the curve of phototrophic growth.