Immobilization of extremophile-derived carbonic anhydrase enzyme onto chitosan-doped polyethylene terephthalate (PET) nanofibres and investigation of its usefulness in carbon dioxide removal

Greenhouse gases accumulated in the atmosphere as a result of industrialization, fossil fuel consumption and various human activities are considered to be one of the main causes of global climate change. One of the most effective of these gases is carbon dioxide (CO2). Today, the removal of CO2 by a biotechnological method is important in the effort against climate change. In this context, carbonic anhydrase (CA) enzyme contributes to the carbon capture process by converting CO2 into bicarbonate ion. In this study, thermophilic CA enzyme isolated from thermal sources was immobilized onto nanofiber structure prepared by using polyethylene terephthalate (PET) and chitosan. Beta class CA enzyme was partially purified from an endospore-forming Gram (+) bacterial strain (E1) of the species Paenibacillus phoenicis by ammonium sulfate precipitation. The surface activity of PET-chitosan nanofibers prepared by electrospinning method was provided with 0.1% glutaraldehyde (GA) solution and then E1 CA enzyme was immobilized on the active surface by covalent binding technique. The highest immobilization efficiency of 52.2% was obtained in PET-chitosan nanofiber containing 15% chitosan concentration with 2 h incubation with GA at 55 ºC followed by 2 h enzyme incubation at 35 ºC. In the storage stability study, it was observed that the immobilized enzyme retained 63% of its activity after 14 days at 60 ºC, but the activity of the free enzyme decreased to 22% under the same conditions. In the fourteen-cycle reusability test, it was determined that the immobilized enzyme retained 49% of its initial activity.