Carbonic anhydrase from extremophiles and their potential use in biotechnological applications

To cope with the extreme habitats, the extremophiles evolved biomolecules adapted to operate under the harsh environmental conditions (high temperature, high salinity, extremes of pH, high pressure, and toxic slots) offering unique biotechnological advantages over their mesophilic counterpart (optimally active at 25°C–50°C), which are often not well suited for the severe reaction conditions required in industrial processes. Recently, a superfamily of metalloenzymes, known as carbonic anhydrases (CAs, EC 4.2.1.1) and catalyzing the CO2 hydration/dehydration reaction, has been investigated in extremophiles since many bacteria are incredibly abundant in environments that are hostile to all other forms of life. In this context, the CAs identified in the genome of Sulfurihydrogenibium yellowstonense and Sulfurihydrogenibium azorense have been investigated for their potential role in biotechnological applications. In particular, the biocatalyst SspCA from S. yellowstonense is a highly active catalyst for the CO2 hydration reaction and extremely thermostable when heated for a prolonged period (more than 180min) to 100°C. For its characteristics the extreme CA could have a pivotal role in fighting the increase of CO2 in the atmosphere caused by the anthropogenic activity. The biomimetic approach of carbon dioxide capture was pursued using the free enzyme or immobilizing it onto polyurethane foam, magnetic particles, ionic liquid membranes, and directly on the external bacterial membrane. In conclusion, the extreme CAs represent an exciting candidate to be used in industrial applications, such as the postcombustion carbon capture process or medical applications, such as in engineering artificial lungs and biosensors.