Enhanced sequestration of carbon dioxide into calcium carbonate using pressure and a carbonic anhydrase from alkaliphilic Coleofasciculus chthonoplastes

Abstract

CO 2 in the atmosphere is a major contributor to global warming but at the same time it has the potential to be a carbon source for advanced biomanufacturing. To utilize CO 2 , carbonic anhydrase has been identified as a key enzyme. Furthermore, attempts have been made to accelerate the sequestration via pressure. This study aims to combine both approaches to achieve high sequestration rates. The carbonic anhydrase of the alkaliphilic cyanobacterium Coleofasciculus chthonoplastes (cahB1) and bovine carbonic anhydrase (BCA) are introduced into a highpressure reactor to catalyze the hydration of CO 2 at up to 20 bar. The reactor is filled with a CaCl 2 solution. Due to the presence of Ca 2+ , the hydrated CO 2 precipitates as CaCO 3 . The impact of the carbonic anhydrase is clearly visible at all pressures tested. At ambient pressure a CO 2 sequestration rate of 243.68 kg CaCO3 /m 3 h for cahB1 was achieved compared to 150.41 kg CaCO3 /m 3 h without enzymes. At 20 bar the rates were 2682.88 and 2267.88 kg CaCO3 /m 3 h, respectively. The study shows the benefit of a combined CO 2 sequestration process. To examinate the influence of the enzymes on the product formation, the precipitated CaCO 3 was analyzed regarding the crystalline phase and morphology. An interchange of the crystalline phase from vaterite to calcite was observed and discussed.

Extracellular CahB1 from Sodalinema gerasimenkoae IPPAS B-353 Acts as a Functional Carboxysomal β-Carbonic Anhydrase in Synechocystis sp. PCC6803

“…The data presented in this study strongly suggest that Sodalinema gerasimenkoae CahB1 acts as a functional carboxysomal β-CA in Synechocystis, which can genetically and physiologically compensate for the loss of the endogenous ccaA/CcaA (Figures 1-3). This is in line with the close sequence similarity that CahB1 bears to Synechocystis CcaA (Figure 1; [26]) and multiple reports of its functionality as an active and efficient CA enzyme [26][27][28]. Depletion of CcaA in the ∆ccaA KD mutant results in a pronounced increase in minimal fluorescence, F o (Figure 2d), which likely indicates a limitation of the acceptor side upon impaired carbon fixation [36][37][38], although the convolution of fluorescence from chlorophyll a with that from phycobiliprotein impair direct interpretation [39].…”

“…In a second instance, the haloalkaliphilic and biofilm-forming Sodalinema gerasimenkoae (formerly Microcoleus / Coleofasciculus chthonoplastes ) has been found to possess active and extracellular CAs [ 24 , 25 ], and the β-CA CahB1 has been shown to localize exclusively to the outer-membrane fraction of the cell [ 26 ]. Moreover, enzymatic CA activity of recombinant CahB1 protein [ 26 ] and its susceptibility to standard CA inhibitors, such as acetazolamide [ 27 ], could be biochemically confirmed, and recently, recombinant CahB1 was also reported to be employed to foster biotechnological calcium carbonate precipitation [ 28 ]. This is well in line with its proposed role in stromatolite formation [ 26 ], and a likely side effect of extracellular CA activity fostering efficient dissolved inorganic carbon uptake in alkaliphilic phototrophic biofilms [ 17 ].…”

Protein inorganic hybrid nanoflowers of a microbial carbonic anhydrase as efficient tool for the conversion of CO2 into value added product

“…The conversion of CO 2 to CaCO 3 was carried out under alkaline conditions. Furthermore, CO 2 hydration and dissolution produce acidity, which, if not buffered, prevents the formation of CaCO 3 precipitates 57 . Interestingly, the CO 2 conversion efficiency of CANF was comparatively higher (94.65 mg CaCO 3 /mg of protein) than that of the CA nanoflowers reported previously (76.27 mg CaCO 3 ) 43 .…”

“…Furthermore, CO 2 hydration and dissolution produce acidity, which, if not buffered, prevents the formation of CaCO 3 precipitates. 57 Interestingly, the CO 2 conversion efficiency of CANF was comparatively higher (94.65 mg CaCO 3 / mg of protein) than that of the CA nanoflowers reported previously (76.27 mg CaCO 3 ). 43 Furthermore, the CA immobilized onto mesoporous aluminosilicate showed 16.14 mg CaCO 3 /mg of protein, which is comparatively lower than the CaCO 3 yield reported in the present study 58 (Table 2).…”

Immobilized Phosphoenolpyruvate Carboxylase Beads for Catalytic Carboxylation in Carbon Dioxide-Containing Gas–Liquid Flow

“…Enzymatic fixation of CO 2 1−3 is one of the promising approaches to mitigate the problems associated with the increasing concentration of atmospheric greenhouse gas. Various enzymes including carbonic anhydrase, 4 formate dehydrogenase, 5 and (de)carboxylase 6 were reported to be applied to catalyze the reactions involving the fixation or conversion CO 2 . Phosphoenolpyruvate carboxylase (PEPC) irreversibly catalyzes the Mg 2+ -dependent formation of oxaloacetate (OAA) and inorganic phosphate (Pi) from phosphoenolpyruvate (PEP) and HCO 3 − .…”