A new type of carboxysomal carbonic anhydrase in sulfur chemolithoautotrophs from alkaline environments

Here, we provide evidence that iota carbonic anhydrase (ιCA) plays a role in CO₂ fixation by some organisms with CO₂-concentrating mechanisms; this is the first time that ιCA has been detected in carboxysomes. While ιCA genes have been previously described in other members of bacteria, this is the first description of a physiological role for this type of carbonic anhydrase in this domain. Given its distribution in alkaliphilic autotrophic bacteria, ιCA may provide an advantage to organisms growing at high pH values and could be helpful for engineering autotrophic organisms to synthesize compounds of industrial interest under alkaline conditions.