Biological CO2 fixation

In contrast to the biological CO2 fixation during the dark reaction of photosynthesis where very low concentrations of CO2 from air can be fixed at room temperature, most reactions with transition-metal complexes or with organic substrates either require high partial pressure of CO2 or high temperatures. An exception was published quite recently, the rapid fixation of CO2 and O2 from air at a palladium(O) complex 10 (Scheme 11) [77]. 

Developing a biological CO2 fixation system for culture ponds in salty water based on the treatment of flue gas from town s utility located on the Black Sea coast would provide the opportunity of using the algae crop as additional fuel to the power station. Advantages are offered by the significant solar radiation that provides a notable daily rate of CO2 fixation. 

The biological CO2 fixation using Chlorella sp. with high capability in fixing CO2... 

Cultivation of cyanobacterium in various types of photobioreactors for biological CO2 fixation... 

Carbon dioxide (CO2), the natural product of fossil-fuel combustion, has been recognized as the main factor for the global warming. Among the various approaches to utilize the CO2 gas, there has been a considerable interest in biological CO2 fixation as a clean and energy-efficient technique [1]. 

Increasing of CO2 in atmosphere is so serious problem for mankind that many R D are implemented to reduce CO2 discharge. One is a biological CO2 fixation using the photosynthetic function of micro-algae. 

This work was performed under the management of Research Institute of Innovative Technology for the Earth (RITE) as a part of the Biological CO2 Fixation and Utilization Project , supported by New Energy and Industrial Technology Development Organization (NEDO). 

Calvin dark cycle pathway a pathway of biological CO2 fixation in which early products are C3 compounds. 

Although the carboxylation of the enol adduct of the aromatic ketones [Eqs. (28) and (29)] is a stoichiometric reaction, these reactions are related to biological CO2 fixation, where the phosphoenolpyruvate product from pyruvate is carboxylated into oxaloacetate ... 

It is estimated that more than 98 % of the CO2 that enters the biological carbon cycle ( 200 Gtc/y) is fixed by carboxylases, which makes them crucial players in controlling atmospheric CO2 concentrations [8, 9]. Biological CO2 fixation can occur following four different pathways [10, 11] ... 

The main isotope-discriminating steps during biological carbon fixation are (1) the uptake and intracellular diffusion of CO2 and (2) the biosynthesis of cellular components. Such a two-step model was first proposed by Park and Epstein (1960) ... 

Biological evolution may have contributed to early Archean oxidation of the Earth. Catling et al., (2001) have recognized that CO2 fixation associated with early photosynthesis may have been coupled with active fermentation and... 

By far the most important biological controls on calcification are those which influence the equilibrium between the inorganic carboxy species (Chapter 2.1, p. 32). This may result from the consumption of CO2 in photosynthesis, chemosynthesis and heterotrophic CO2 fixation the release of CO2 during respiration and fermentation and from the production of bases and acids due to varied metabolic activities. 

These potent biological reductants and oxidants provide all the energy needed to drive all subsequent reactions of photosynthesis electron transport, ATP synthesis, and CO2 fixation. 

The bacterial metalloenzyme acetyl coenzyme A synthase/CO dehydrogenase (ACS/CODH) catalyzes two very important biological processes, namely the reduction of atmospheric CO2 to CO and the synthesis of acetyl coerrzyme A from CO, a methyl from a methylated corrinoid iron-sulfur protein, and the thiol coenzyme A [166-168]. This bifunctional errzyme is the key to the Wood-Ljiungahl pathway of anaerobic CO2 fixation (Scheme 1.18) and a major component of the global carbon cycle. Reactions catalyzed by CODH and ACS are shown in Eqs. (1.4) and (1.5) below. 

End-on (q -OCO) coordination mode has remained elusive for a long time. Nevertheless, this coordination mode may play an important role in biological systems. In photosynthetic CO2 fixation, an oxygen-bound CO2 ligand has been proposed to be enzymatically reduced by ilbulose-1,5-biphosphate carboxylase-oxygenase (RuBisCO) [47]. A crystallographic study on a deacetoxycephalosporin C synthase (DAOCS) mutant showed the presence of electron density close to the iron center of the active site, which was found to be consistent with the presence of a monodentate O-coordinated CO2 molecule [48]. 

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