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Carbon Dioxide Sequestration by Microalgae
Published in Gokare A. Ravishankar, Ranga Rao Ambati, Handbook of Algal Technologies and Phytochemicals, 2019
G.V. Swarnalatha, Ajam Shekh, P.V. Sijil, C.K. Madhubalaji, Vikas Singh Chauhan, Ravi Sarada
RuBisCO is present as a soluble protein in the chloroplast stroma of higher plants. But in microalgae, it is present in the pyrenoid of the chloroplast. In cyanobacteria it is present in carboxysomes that are surrounded by a protein shell and are rich in electron dense particles. The primary location of RuBisCO is carboxysomes in cyanobacteria (McKay et al. 1993) (Table 6.1).
Biology of microbes
Published in Philip A. Geis, Cosmetic Microbiology, 2006
Cytoplasm, mesosomes, ribosomes, and other inclusions. A bacterial cell minus its wall is a protoplast. A protoplast includes the plasma membrane, the cytoplasm, and everything within it. The prokaryotic cytoplasm, however, does not have typical unit membrane-bound internal organelles. Within the cytoplasm is the nucleoid where the DNA genetic material is localized. Also, within the cytoplasm are the enzymes needed for growth and metabolism, the machinery for manufacturing those enzymes (ribosomes), and some internal membrane structures called mesosomes. Mesosomes are actually invaginations of the plasma membrane. Finally, some bacteria also contain inclusion bodies consisting of polyphosphate, cyanophycin, and glycogen. These inclusions are not usually membrane-bound. Other bacteria have inclusions bound by a single-layered nonunit membrane. These consist of poly-b-hydroxybutyrate, sulfur, carboxysomes, hydrocarbons, and gas vacuoles.
An overview on the recently discovered iota-carbonic anhydrases
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2021
Alessio Nocentini, Claudiu T. Supuran, Clemente Capasso
In plants, CO2 is stored as bicarbonate ions. In both terrestrial and aquatic plants, CA converts HCO3- ions to CO2, which is concentrated in the proximity of the enzyme RuBisCO (Ribulose Bisphosphate Carboxylase/Oxygenase) present in the stroma of the chloroplasts13–15. As a result, the performance of RuBisCO carboxylation reaction is increased, whereas its oxygenation is suppressed. Eukaryotic unicellular photosynthetic organisms have evolved diverse Carbon Concentrating Mechanisms (CCMs) to increase CO2 concentration in the proximity of RuBisCO up to 1000-fold from the low CO2 levels present in the environment. In algae, the main component of the CCM is the pyrenoid16,17. In cyanobacteria, the equivalent of the pyrenoid is the carboxysome. Carboxysomes are composed of RuBisCO, CAs, active bicarbonate transporters, and structural envelope proteins18. The structure of the carboxysome envelope prevents the escape of CO2 from these organelles.
Characterization of planktonic and biofilm cells from two filamentous cyanobacteria using a shotgun proteomic approach
Published in Biofouling, 2020
Maria João Leal Romeu, Dany Domínguez-Pérez, Daniela Almeida, João Morais, Alexandre Campos, Vítor Vasconcelos, Filipe J. M. Mergulhão
Moreover, for both cyanobacterial strains, in biofilms formed on perspex and at 4 s−1 a protein involved in the formation of the carboxysome (carbon dioxide-concentrating mechanism protein CcmK) was also found. Carboxysomes are polyhedral inclusion where the ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco; the central enzyme in photosynthetic carbon assimilation) is sequestered. The CO2 concentrating mechanism (CCM) is an adaptive and effective strategy evolved in cyanobacteria and also in eukaryotic microalgae for carbon acquisition, and it enables these organisms to survive when the CO2 concentration limits photosynthesis (Wang et al. 2015). Baba et al. (2011) also studied this mechanism in the unicellular green alga Chlamydomonas reinhardtii. When the CO2 concentration was elevated from the ambient air level to 3%, the algal growth rate increased 1.5-fold, and the amount and the composition of extracellular proteins clearly changed. However, significant changes were not found in intracellular proteins (Baba et al. 2011). In a study performed by Slabas et al. (2006), a decrease in Rubisco proteins was observed after heat shock in Synechocystis PCC 6803. Moreover, the CCM is a fundamental aspect of photosynthesis, metabolism, growth and biomass production in photosynthetic organisms and understanding this process provides guidance for potential molecular manipulation to improve biomass yield for commercial applications (Badger and Price 2003).
Use of an immobilised thermostable α-CA (SspCA) for enhancing the metabolic efficiency of the freshwater green microalga Chlorella sorokiniana
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2020
Giovanna Salbitani, Sonia Del Prete, Francesco Bolinesi, Olga Mangoni, Viviana De Luca, Vincenzo Carginale, William A. Donald, Claudiu T. Supuran, Simona Carfagna, Clemente Capasso
Microalgal growth is driven by the same photosynthetic process present in higher plants12–15. Both freshwater and marine microalgae, also developed a CCM to increase CO2 concentration close to that for RuBisCO that is up to 1000-fold compared to the low CO2 concentrations found in aquatic environments16. In the single-cell green alga, Chlamydomonas reinhardtii, the microalgal inorganic carbon uptake has been well described17,18. It involves the diffusion of CO2 and transport of HCO3− across the microalgal membranes and the interconversion of CO2 and HCO3− by the algal carbonic anhydrases (CAs, EC 4.2.1.1), with the final result of concentrating the CO2 in the proximity of RuBisCO17, which is localised mostly within the pyrenoids, the chloroplast microcompartments found in algae19–23. In cyanobacteria, carboxysomes are the equivalent of the pyrenoids24–27.