Deep eutectic systems for carbonic anhydrase extraction from microalgae biomass to improve carbon dioxide solubilization

Abstract

This work is the first proof-of-concept of the use of carbonic anhydrase (CA) enzyme from microalgae biomass, extracted with deep eutectic systems (DES), with the goal of engineering a solution that will lead to a breakthrough in the Carbon Capture and Utilization (CCU) strategy. Three distinct microalgae were processed - Tisochrysis lutea, Chlorella vulgaris, and Spirulina sp. - with three DES - Choline chloride-Urea (ChCl-U), Choline chloride-Poly(ethylene glycol) (ChCl-PEG), and Poly(ethylene glycol)-Urea (PEG-U). To evaluate the most promising microalgae-DES, CA activity was evaluated with a specific enzymatic activity kit and through CO2 solubility assays. Preliminary results indicate that: DES is a suitable solvent medium for CA extraction from microalgal biomass, preserving its activity (specific CA activity up to 0.70 mU.mg(-1)); CA extraction efficiency differs between DES and microalgal species, indicating the potential for further research; from the tested DES, the ones containing PEG were favorable to maintain CA activity (CO2 solubility up to 4 g CO2.g(-1) DES). This work paves the way towards a disruptive CCU approach.