Molecular characterization of the thermostability and carbohydrate-binding module from a newly identified GH118 family agarase, AgaXa

•AgaXa mutants were generated via the random and site-directed mutagenesis.•The crucial amino acids related to thermostability and enzymatic activity were demonstrated.•The location of carbohydrate-binding site was identified from the truncated mutants of AgaXa.•Molecular mechanism of this new agarase member in GH118 family was firstly investigated.