CO2(aq) concentration–dependent CO2 fixation via carboxylation by decarboxylase

2021 ◽  
Author(s):  
Yan Fan ◽  
Jianqiang Feng ◽  
miao yang ◽  
xin Tan ◽  
Hongjun Fan ◽  
...  
Keyword(s):  
Co2 Sequestration ◽  
Co2 Fixation ◽  
Carbon Fixation ◽  
Decarboxylation Reaction

Enzymatic carbon fixation is one of the most interesting processes in CO2 sequestration. A number of decarboxylases can catalyze the reversible decarboxylation reaction in vivo, while can strengthen the carboxylation...

Sectioned rubisco crystals in TEM

1990 ◽  
Vol 48 (3) ◽  
pp. 664-665
Author(s):  
Gunnel Karlsson ◽  
Jan-Olov Bovin ◽  
Michael Bosma
Keyword(s):  
Plant Cell ◽  
Carbon Fixation ◽  
Unit Cell ◽  
Protein Crystals ◽  
Unit Cell Parameters ◽  
Cell Parameters ◽  
Photosynthetic Carbon Fixation ◽  
Photosynthetic Carbon

RuBisCO (D-ribulose-l,5-biphosphate carboxylase/oxygenase) is the most aboundant enzyme in the plant cell and it catalyses the key carboxylation reaction of photosynthetic carbon fixation, but also the competing oxygenase reaction of photorespiation. In vitro crystallized RuBisCO has been studied earlier but this investigation concerns in vivo existance of RuBisCO crystals in anthers and leaves ofsugarbeets. For the identification of in vivo protein crystals it is important to be able to determinethe unit cell of cytochemically identified crystals in the same image. In order to obtain the best combination of optimal contrast and resolution we have studied different staining and electron accelerating voltages. It is known that embedding and sectioning can cause deformation and obscure the unit cell parameters.

scholarly journals Insights into Autotrophic Activities and Carbon Flow in Iron-Rich Pelagic Aggregates (Iron Snow)

2021 ◽  
Vol 9 (7) ◽  
pp. 1368
Author(s):  
Qianqian Li ◽  
Rebecca E. Cooper ◽  
Carl-Eric Wegner ◽  
Martin Taubert ◽  
Nico Jehmlich ◽  
...  
Keyword(s):  
Transcriptional Activity ◽  
Co2 Fixation ◽  
Carbon Fixation ◽  
Stable Isotope Probing ◽  
Acidic Lake ◽  
General Role ◽  
Polysaccharide Biosynthesis ◽  
Iron Oxidizers ◽  
Metabolic Activities ◽  
Chemolithoautotrophic Bacteria

Pelagic aggregates function as biological carbon pumps for transporting fixed organic carbon to sediments. In iron-rich (ferruginous) lakes, photoferrotrophic and chemolithoautotrophic bacteria contribute to CO2 fixation by oxidizing reduced iron, leading to the formation of iron-rich pelagic aggregates (iron snow). The significance of iron oxidizers in carbon fixation, their general role in iron snow functioning and the flow of carbon within iron snow is still unclear. Here, we combined a two-year metatranscriptome analysis of iron snow collected from an acidic lake with protein-based stable isotope probing to determine general metabolic activities and to trace 13CO2 incorporation in iron snow over time under oxic and anoxic conditions. mRNA-derived metatranscriptome of iron snow identified four key players (Leptospirillum, Ferrovum, Acidithrix, Acidiphilium) with relative abundances (59.6–85.7%) encoding ecologically relevant pathways, including carbon fixation and polysaccharide biosynthesis. No transcriptional activity for carbon fixation from archaea or eukaryotes was detected. 13CO2 incorporation studies identified active chemolithoautotroph Ferrovum under both conditions. Only 1.0–5.3% relative 13C abundances were found in heterotrophic Acidiphilium and Acidocella under oxic conditions. These data show that iron oxidizers play an important role in CO2 fixation, but the majority of fixed C will be directly transported to the sediment without feeding heterotrophs in the water column in acidic ferruginous lakes.

scholarly journals The carbon fixation efficiency in biomass of Cylindrotheca closterium (Ehrenberg) Reimann & J. C. Lewin (Bacillariophyceae) under the conditions of cumulative cultivation

2020 ◽  
Vol 5 (1) ◽  
pp. 12-19
Author(s):  
R. G. Gevorgiz ◽  
S. N. Zheleznova
Keyword(s):  
Co2 Fixation ◽  
Carbon Fixation ◽  
Utilization Efficiency ◽  
Chlorella Protothecoides ◽  
Carbonic Anhydrases ◽  
Low Carbon ◽  
Carbon Utilization ◽  
Porphyridium Purpureum ◽  
Cylindrotheca Closterium ◽  
Dry Biomass

The carbon utilization efficiency is an important characteristic of the cultivated object. Diatom Cylindrotheca closterium (Ehrenberg) Reimann & J. C. Lewin is known to use carbon from aquatic environment quite effectively, as it has many unique carbonic anhydrases and carbon transporters. However, the carbon fixation efficiency for many types of diatoms in culture is still unknown. When calculating the carbon fixation efficiency, researchers use different terminology and methods, and it leads to significant difficulties when comparing the carbon fixation efficiency in the biomass of various types of microalgae. The aims of this study are: 1) to update terms and definitions used in literature on the basis of modern concepts of carbon fixation in microalgae biomass, as well as absorption of inorganic carbon by microalgae culture; 2) to evaluate the carbon fixation efficiency in the biomass of C. closterium diatom under conditions of cumulative cultivation. C. closterium was grown at a temperature of +20 °C on a nutrient medium RS. During the cultivation, the culture was bubbled with air (1.1 L of air per 1 L of culture per minute). The air temperature at the outlet of the suspension was of +19 °C; the maximum productivity of the culture was of 1.254 g·L−1·day−1. According to the results of the CHN analysis, the proportion of carbon in C. closterium dry biomass was of 23 %. Under the conditions of cumulative cultivation in C. closterium, the carbon fixation efficiency in biomass was of 90 %. Compared with other algae species, C. closterium is characterized by a rather high CO2 fixation efficiency. For example, in green microalga Chlorella protothecoides and Ch. vulgaris, the CO2 fixation efficiency was of 20 % and 55.3 %, respectively; in cyanobacteria Spirulina sp. – of 38 %; in red microalgae Porphyridium purpureum – of 69 %. It was observed that to ensure an increase of 1 g of C. closterium dry biomass per day at a temperature of +19 °C, a minimum of 0.46 L of CO2, or 1132 L of air, should be consumed. Possibly, it is high carbon fixation efficiency, as well as low carbon fraction in C. closterium biomass, that explains the high production indices of this species. Under equal conditions of cultivation in terms of light and carbon availability, the productivity of C. closterium can exceed the productivity of other types of microalgae by 5–10 times. So, while Spirulina sp. productivity reaches 0.2 g·L−1·day−1, C. closterium productivity is of 1.254 g·L−1·day−1.

Quantum Yield of Photosystem II and Efficiency of CO2 Fixation in Flaveria (Asteraceae) Species under Varying Light and CO2

1991 ◽  
Vol 18 (4) ◽  
pp. 369 ◽  
Author(s):  
JP Krall ◽  
GE Edwards ◽  
MSB Ku
Keyword(s):  
Quantum Yield ◽  
Photosystem Ii ◽  
Co2 Fixation ◽  
C4 Photosynthesis ◽  
Co2 Assimilation ◽  
Quantum Yields ◽  
Progressive Development ◽  
Psii Activity ◽  
C3 And C4 Photosynthesis

The quantum yields of electron transport from photosystem II (PSII) (Φe, determined from chlorophyll a fluorescence), and CO2 assimilation (ΦCO2, photosynthetic rate/light intensity) were measured simultaneously in vivo with representative species of Flaveria which show a progression in development between C3 and C4 photosynthesis and in reduction of photorespiration. These were F. pringlei (C3), F. sonorensis (C3-C4, but lacking a C4 cycle), F. floridana (C3-C4, with partially functional C4 cycle), F. brownii (C4-like) and F. bidentis (C4). The level of PSII activity with varying CI under 210 mbar O2 was very similar in all species. However, the progressive development of C4 characteristics among the species produced an increased efficiency in utilisation of PSII derived energy for CO2 assimilation under 210 mbar O2, due to reduced photorespiratory losses at low CO2 levels. In all species, when photorespiration was limited by low O2 (20 mbar), there was a linear or near linear relationship between the quantum yield of PSII v. the quantum yield of CO2 fixation with varying intercellular levels of CO2 (Ci) indicating that CO2 fixation in this case is linked to PSII activity. When switching from 20 to 210 mbar O2 at atmosphere levels of CO2, there was a similar decrease in the efficiency in utilising PSII activity for CO2 assimilation at different light intensities, but the degree of sensitivity to O2 progressively decreased among the species concomitant with the development of C4 photosynthesis. These results may help explain why there is an advantage to evolution of C4 photosynthesis in environments where Ci becomes limiting.

scholarly journals Balancing energy supply during photosynthesis - a theoretical perspective

2018 ◽  
Author(s):  
Anna Matuszyńska ◽  
Nima P. Saadat ◽  
Oliver Ebenhöh
Keyword(s):  
Molecular Mechanisms ◽  
Carbon Fixation ◽  
Supply And Demand ◽  
Theoretical Perspective ◽  
Photosynthetic Electron Transport ◽  
C3 Plants ◽  
Photochemical Quenching ◽  
Dark Light ◽  
Dynamic Description

The photosynthetic electron transport chain (PETC) provides energy and redox equivalents for carbon fixation by the Calvin-Benson-Bassham (CBB) cycle. Both of these processes have been thoroughly investigated and the underlying molecular mechanisms are well known. However, it is far from understood by which mechanisms it is ensured that energy and redox supply by photosynthesis matches the demand of the downstream processes. Here, we deliver a theoretical analysis to quantitatively study the supply-demand regulation in photosynthesis. For this, we connect two previously developed models, one describing the PETC, originally developed to study non-photochemical quenching, and one providing a dynamic description of the photosynthetic carbon fixation in C3 plants, the CBB Cycle. The merged model explains how a tight regulation of supply and demand reactions leads to efficient carbon fixation. The model further illustrates that a stand-by mode is necessary in the dark to ensure that the carbon fixation cycle can be restarted after dark-light transitions, and it supports hypotheses, which reactions are responsible to generate such mode in vivo.

scholarly journals Preliminary Investigation of CO2 Sequestration by Chlorella sorokiniana TH01 in Single and Sequential Photobioreactors

2020 ◽  
Vol 36 (1) ◽  
Author(s):  
Do Thi Cam Van ◽  
Tran Dang Thuan ◽  
Nguyen Quang Tung
Keyword(s):  
Co2 Sequestration ◽  
Fossil Fuels ◽  
Co2 Fixation ◽  
Preliminary Investigation ◽  
Co2 Concentration ◽  
Maximum Growth ◽  
Chlorella Sorokiniana ◽  
Effective Utilization ◽  
Sequestration Of Co2 ◽  
Wide Range

Increasing accumulation of CO2 in the atmosphere mainly caused by fossil fuels combustion of human activities have resulted in adverse global warming. Therefore, searching for treatment methods for effective utilization of CO2 have received a great attention worldwide. Among various methods (e.g., adsorption, absorption, storage, membrane technologies, etc.) have been developed and applied, the sequestration of CO2 using microalgae has recently emerged as an alternatively sustainable approach. In this work, a green microalgal strain Chlorella sorokiniana TH01 was used to investigate its capability in sequestration of CO2 in laboratory scale. Results indicated that the C. sorokiniana TH01 grew well under a wide range of CO2 concentration from 0.04% to 20% with maximum growth was achieved under CO2 aeration of 15%. In a single photobioreactor (PBR) with 10 min empty bed residence time (EBRT), the C. sorokiniana TH01 only achieved CO2 fixation efficiency of 6.33% under continuous aeration of 15% CO2. Increasing number of PBRs to 15 and connected in a sequence enhanced mean CO2 fixation efficiency up to 82.64%. Moreover, the CO2 fixation efficiency was stable in the range of 78.67 to 91.34% in 10 following days of the cultivation. Removal efficiency of NO3--N and PO43--P reached 82.54 – 90.25% and 95.33 – 98.02%, respectively. Our trial data demonstrated that the C. sorokiniana TH01 strain is a promising microalgal for further research in simultaneous CO2 mitigation via CO2 sequestration from flue gas as well as nutrients recycling from wastewaters. Keywords: Carbon dioxide, C. sorokiniana TH01, Photobioreactors, Sequestration, Nutrients removal.

scholarly journals Dissection of the ATPase active site of McdA reveals the sequential steps essential for carboxysome distribution

2021 ◽  
pp. mbc.E21-03-0151
Author(s):  
Pusparanee Hakim ◽  
Y Hoang ◽  
Anthony G. Vecchiarelli
Keyword(s):  
Active Site ◽  
Carbon Fixation ◽  
Binding Region ◽  
Two Component System ◽  
Component System ◽  
Ratchet Mechanism ◽  
Bacterial Microcompartment ◽  
Two Component ◽  
Bacterial Nucleoid

Carboxysomes, the most prevalent and well-studied anabolic bacterial microcompartment, play a central role in efficient carbon fixation by cyanobacteria and proteobacteria. In previous studies, we identified the two-component system called McdAB that spatially distributes carboxysomes across the bacterial nucleoid. McdA, a ParA-like ATPase, forms a dynamic oscillating gradient on the nucleoid in response to carboxysome-localized McdB. As McdB stimulates McdA ATPase activity, McdA is removed from the nucleoid in the vicinity of carboxysomes, propelling these proteinaceous cargos toward regions of highest McdA concentration via a Brownian-ratchet mechanism. How the ATPase cycle of McdA governs its in vivo dynamics and carboxysome positioning remains unresolved. Here, by strategically introducing amino acid substitutions in the ATP-binding region of McdA, we sequentially trap McdA at specific steps in its ATP cycle. We map out critical events in the ATPase cycle of McdA that allows the protein to bind ATP, dimerize, change its conformation into a DNA-binding state, interact with McdB-bound carboxysomes, hydrolyze ATP and release from the nucleoid. We also find that McdA is a member of a previously unstudied subset of ParA family ATPases, harboring unique interactions with ATP and the nucleoid for trafficking their cognate intracellular cargos. [Media: see text] [Media: see text] [Media: see text]

scholarly journals Dissection of the ATPase active site of McdA reveals the sequential steps essential for carboxysome distribution

2021 ◽  
Author(s):  
Pusparanee Hakim ◽  
Anthony G. Vecchiarelli
Keyword(s):  
Active Site ◽  
Carbon Fixation ◽  
Binding Region ◽  
Two Component System ◽  
Component System ◽  
Ratchet Mechanism ◽  
Bacterial Microcompartment ◽  
Two Component ◽  
Bacterial Nucleoid

ABSTRACTCarboxysomes, the most prevalent and well-studied anabolic bacterial microcompartment, play a central role in efficient carbon fixation by cyanobacteria and proteobacteria. In previous studies, we identified the two-component system called McdAB that spatially distributes carboxysomes across the bacterial nucleoid. McdA, a ParA-like ATPase, forms a dynamic oscillating gradient on the nucleoid in response to carboxysome-localized McdB. As McdB stimulates McdA ATPase activity, McdA is removed from the nucleoid in the vicinity of carboxysomes, propelling these proteinaceous cargos toward regions of highest McdA concentration via a Brownian-ratchet mechanism. However, how the ATPase cycle of McdA governs its in vivo dynamics and carboxysome positioning remains unresolved. Here, by strategically introducing amino acid substitutions in the ATP-binding region of McdA, we sequentially trap McdA at specific steps in its ATP cycle. We map out critical events in the ATPase cycle of McdA that allows the protein to bind ATP, dimerize, change its conformation into a DNA-binding state, interact with McdB-bound carboxysomes, hydrolyze ATP and release from the nucleoid. We also find that McdA is a member of a previously unstudied subset of ParA family ATPases, harboring unique interactions with ATP and the nucleoid for trafficking their cognate intracellular cargos.

scholarly journals Release and fixation of CO2 by guinea-pig kidney tubules metabolizing aspartate

1992 ◽  
Vol 284 (3) ◽  
pp. 697-703
Author(s):  
G Martin ◽  
C Michoudet ◽  
N Vincent ◽  
G Baverel
Keyword(s):  
Guinea Pig ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Co2 Fixation ◽  
Carbon Oxidation ◽  
Kidney Tubules ◽  
Pig Kidney ◽  
Glutamine Synthesis ◽  
Oxoglutarate Dehydrogenase

1. The metabolism of L-[U-14C]aspartate, L-[1-14C]aspartate and L-[4-14C]aspartate was studied in isolated guinea-pig kidney tubules. 2. Oxidation of C-1 plus that of C-4 of aspartate accounted for 90-92% of the CO2 released from aspartate, whereas oxidation of the inner carbon atoms of aspartate (which occurs beyond the 2-oxoglutarate dehydrogenase step) represented only 8-10% of aspartate carbon oxidation. 3. The formation of [1-14C]glutamine and [1-14C]glutamate from [1-14C]aspartate and [4-14C]aspartate indicated that about one-third of the oxaloacetate synthesized from aspartate underwent randomization at the level of fumarate. 4. With [U-14C]aspartate as substrate, the percentage of the C-1 of glutamate and glutamine found radiolabelled after 60 min of incubation was 92.7% and 47.5% in the absence and the presence of bicarbonate respectively. 5. That CO2 fixation occurred at high rates in the presence of bicarbonate was demonstrated by incubating tubules with aspartate plus [14C]bicarbonate; under this condition, the label fixed was found in C-1 of glutamate, glutamine and aspartate, as well as in C-4 of aspartate, demonstrating not only randomization of aspartate carbon but also aspartate resynthesis secondary to oxaloacetate cycling via phosphoenolpyruvate carboxykinase, pyruvate kinase and pyruvate carboxylase. 6. The importance of CO2 fixation in glutamine synthesis from aspartate is discussed in relation to the possible role of the guinea-pig kidney in systemic acid-base regulation in vivo.

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