Presentation Information
[P04-528]Immobilized carbonic anhydrase as stable catalyst in bubble column bioreactors
○Makoto Yoshimoto1, Fumiya Tanaka1, Shoma Nii1 (1. Yamaguchi University (Japan))
Keywords:
Immobilized enzyme,Multiphase bioreactor,Bubble column
[Purpose]
Carbonic anhydrase (CA) is the enzyme that efficiently catalyzes the hydration of carbon dioxide. CA is potentially useful for performing carbon fixation-relevant catalytic reactions under physiological conditions. The conformation and catalytic activity of CA need to be maintained in the presence of dispersed bubbles when gaseous carbon dioxide is employed as the source of enzyme substrate. In the present work, water-insoluble carrier-immobilized CA was prepared and its characteristics including the stability in a multiphase flow were examined.
[Method]
An external loop gas-lift bubble column (ELBC) was used to generate gas-liquid or gas-liquid-solid flow. CA was immobilized onto reactive lipids-incorporated phospholipid vesicles (liposomes) via amide bonds followed by the purification with the size exclusion chromatography. CA-liposome conjugates were dispersed in ELBC at 25 °C. Gas phase consisting of 10% carbon dioxide and 90% nitrogen was introduced to ELBC in the form of millibubbles at the superficial gas velocity of 1.0 cm/s.
[Results]
In the static liquid system without gas bubbling, both free and liposome-conjugated CA were stable for 120 min in their esterase activity measured with 1.0 mM p-nitrophenyl acetate as the substrate. The deactivation of free CA was accelerated in ELBC showing almost no activity after the operation time of 60 min, whereas liposome-conjugated CA exhibited about 35% of the initial activity after 120 min in ELBC.
[Consideration]
Free CA was indicated to be deactivated through hydrophobic interaction with gas-liquid interface. On the other hand, the adsorptive interaction between CA and gas-liquid interface was suggested to be weakened by conjugating CA to hydrophilic surface of liposomes. The polymeric microbeads covalently immobilized with CA were also prepared for comparison and their operational stability and performance in catalyzing the carbon dioxide hydration were examined using ELBC as a gas-liquid-solid-contacting bioreactor.
[Conclusion]
Immobilized CA was found to possess high operational stability in the bubble column bioreactor and thus useful for catalytic hydration of gaseous carbon dioxide.
Carbonic anhydrase (CA) is the enzyme that efficiently catalyzes the hydration of carbon dioxide. CA is potentially useful for performing carbon fixation-relevant catalytic reactions under physiological conditions. The conformation and catalytic activity of CA need to be maintained in the presence of dispersed bubbles when gaseous carbon dioxide is employed as the source of enzyme substrate. In the present work, water-insoluble carrier-immobilized CA was prepared and its characteristics including the stability in a multiphase flow were examined.
[Method]
An external loop gas-lift bubble column (ELBC) was used to generate gas-liquid or gas-liquid-solid flow. CA was immobilized onto reactive lipids-incorporated phospholipid vesicles (liposomes) via amide bonds followed by the purification with the size exclusion chromatography. CA-liposome conjugates were dispersed in ELBC at 25 °C. Gas phase consisting of 10% carbon dioxide and 90% nitrogen was introduced to ELBC in the form of millibubbles at the superficial gas velocity of 1.0 cm/s.
[Results]
In the static liquid system without gas bubbling, both free and liposome-conjugated CA were stable for 120 min in their esterase activity measured with 1.0 mM p-nitrophenyl acetate as the substrate. The deactivation of free CA was accelerated in ELBC showing almost no activity after the operation time of 60 min, whereas liposome-conjugated CA exhibited about 35% of the initial activity after 120 min in ELBC.
[Consideration]
Free CA was indicated to be deactivated through hydrophobic interaction with gas-liquid interface. On the other hand, the adsorptive interaction between CA and gas-liquid interface was suggested to be weakened by conjugating CA to hydrophilic surface of liposomes. The polymeric microbeads covalently immobilized with CA were also prepared for comparison and their operational stability and performance in catalyzing the carbon dioxide hydration were examined using ELBC as a gas-liquid-solid-contacting bioreactor.
[Conclusion]
Immobilized CA was found to possess high operational stability in the bubble column bioreactor and thus useful for catalytic hydration of gaseous carbon dioxide.
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