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    Transcriptome aberration in marine microalgae Phaeodactylum tricornutum induced by commercial naphthenic acids
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    Keywords:
    Phaeodactylum tricornutum
    Photosynthetic efficiency
    Metabolic pathway
    Carbon fixation
    In the present paper,chlorophyll content and the photosynthesis efficiency change of the tea in different kinds and different leaves of 3 years young shoot were determined and analyzed on the autumn same condition.The results indicated that the different kinds and the different leaves'chlorophyll content had highly significant correlations.The fourth leaf and Nanjiangdayecha had the highest content of chlorophyll.And the highest the photosynthesis efficiency(Fv/Fm,Fv/Fo) expression was in the third leaf and Fudingdabaicha,obviously the content of chlorophyll was not completely consistent with the photochemistry efficiency.It was highly significantly negative correlations at the 4th and 5th leaf.The 4th and 5th leafs'chlorophyll b content could be considered one of important selection indexes on high photochemistry efficiency.
    Photosynthetic efficiency
    Chlorophyll b
    Citations (0)
    Optimizing designer metabolisms in vitro Biological carbon fixation requires several enzymes to turn CO 2 into biomass. Although this pathway evolved in plants, algae, and microorganisms over billions of years, many reactions and enzymes could aid in the production of desired chemical products instead of biomass. Schwander et al. constructed an optimized synthetic carbon fixation pathway in vitro by using 17 enzymes—including three engineered enzymes—from nine different organisms across all three domains of life (see the Perspective by Gong and Li). The pathway is up to five times more efficient than the in vivo rates of the most common natural carbon fixation pathway. Further optimization of this and other metabolic pathways by using similar approaches may lead to a host of biotechnological applications. Science , this issue p. 900 ; see also p. 830
    Carbon fixation
    Metabolic pathway
    Synthetic Biology
    Metabolic Engineering
    Citations (584)
    Abstract The CO 2 concentration at ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is crucial to improve photosynthetic efficiency for biomass yield. However, how to concentrate and transport atmospheric CO 2 towards to the Rubisco carboxylation is a big challenge. Here in, we report the self-assembly of metal-organic frameworks (MOFs) on the surface of a microalgae that can greatly enhance the photosynthetic efficiency. The non-genetic concentrating CO 2 approach improved photosynthetic efficiency by about 2 folds, which is up to 7.5% in ambient air from an intrinsic 3.6%. We find that the efficient carbon fixation lies in the conversion of the captured CO 2 to the transportable HCO 3 - species at bio-organic interface. This work demonstrated a non-genetic approach of concentrating atmospheric CO 2 for enhancing biomass yield of photosynthesis.
    Carbon fixation
    Photosynthetic efficiency
    Carboxylation
    :Little is known about the combined impacts of temperature increases and fluctuating radiation regimes on the photosynthetic capability of marine diatoms. We incubated Phaeodactylum tricornutum cells under normal (18°C) vs elevated temperature (+6°C) in semicontinuous cultures and exposed them to fixed and fluctuating radiation conditions. Photosynthetic performance was determined based on the effective quantum yield of open photosystem II (PSII; F′V/F′M), the maximum relative electron transport rate (rETRmax), the light saturation parameter (Ek) and the photosynthetic efficiency parameter (α). These photophysiological parameters were affected more by irradiance than by the increase of temperature when P. tricornutum cells were exposed to fixed light regimes, and there was no significant difference between temperature treatments. In contrast, under fluctuating radiation regimes, the impact of temperature was clearly evident. Cells incubated at high temperature showed higher F′V/F′M, rETRmax and α but lower Ek when exposed to fast cycling in irradiance (20 min per cycle). In addition, cells grown at high temperature possessed a smaller value of effective target size for photoinactivation of PSII (σi), particularly for cells exposed to fast cycling in irradiance. This indicated that they were more resistant to PSII photoinactivation. These results showed that the photosynthetic capacity of P. tricornutum cells could be favoured by the increase of temperature, and fast cycling in irradiance increased the ability of cells to use the light and provoked much less photoinactivation.
    Phaeodactylum tricornutum
    Photosynthetic efficiency
    Photoinhibition
    Citations (5)
    Unbuffered and nutrient-replete dilute batch cultures of Skeletonema costatum Cleve and Phaeodactylum tricornutum Bohlin were grown at high and low CO 2 availability conditions and two incident irradiances, 150 and 30 µmol photons·m –2 ·s –1 . Long-term combined effects of such light and CO 2 availability conditions on carbon fixation rates of both diatoms were compared. At saturating light, P. tricornutum showed higher photosynthetic rates than S. costatum at both CO 2 conditions. However, under subsaturating light, carbon fixation rates of P. tricornutum were higher than observed for S. costatum only at low CO 2 . Skeletonema costatum showed a strong reduction in photosynthetic rates only when both resources, irradiance and CO 2 , were low. Short-term alterations of light and CO 2 availability on carbon fixation showed that the response of S. costatum differed considerably from long-term trends: the short-term reduction in CO 2 availability at both light levels resulted in a considerable decrease in the maximum photosynthetic rates. This effect was much less noticeable in P. tricornutum. The results show that, at saturating light, both diatoms maintain maximum photosynthetic rates under low CO 2 levels, but only P. tricornutum is well adapted to rapid changes in this resource. This capacity of adaptation seems to be light dependent, since light limitation altered the responses of both diatoms to low CO 2 availability conditions.Key words: CO 2 , 14 C fixation, irradiance, Phaeodactylum tricornutum, Skeletonema costatum.
    Phaeodactylum tricornutum
    Carbon fixation
    Citations (8)
    Ocean acidification (OA) due to atmospheric CO2 rise is expected to influence marine primary productivity. In order to investigate the interactive effects of OA and light changes on diatoms, we grew Phaeodactylum tricornutum, under ambient (390 ppmv; LC) and elevated CO2 (1000 ppmv; HC) conditions for 80 generations, and measured its physiological performance under different light levels (60 µmol m(-2) s(-1), LL; 200 µmol m(-2) s(-1), ML; 460 µmol m(-2) s(-1), HL) for another 25 generations. The specific growth rate of the HC-grown cells was higher (about 12-18%) than that of the LC-grown ones, with the highest under the ML level. With increasing light levels, the effective photochemical yield of PSII (Fv'/Fm') decreased, but was enhanced by the elevated CO2, especially under the HL level. The cells acclimated to the HC condition showed a higher recovery rate of their photochemical yield of PSII compared to the LC-grown cells. For the HC-grown cells, dissolved inorganic carbon or CO2 levels for half saturation of photosynthesis (K1/2 DIC or K1/2 CO2) increased by 11, 55 and 32%, under the LL, ML and HL levels, reflecting a light dependent down-regulation of carbon concentrating mechanisms (CCMs). The linkage between higher level of the CCMs down-regulation and higher growth rate at ML under OA supports the theory that the saved energy from CCMs down-regulation adds on to enhance the growth of the diatom.
    Phaeodactylum tricornutum
    Photosynthetic efficiency
    Ocean Acidification