Stabilized and Immobilized Bacillus subtilis Arginase for the Biobased Production of Nitrogen‐Containing Chemicals

L‐Ornithine could serve as an intermediate in the biobased production of 1,4‐diaminobutane from L‐arginine. Using the concept of biorefinery, L‐arginine could become widely available from biomass waste streams via the nitrogen storage polypeptide cyanophycin. Selective hydrolysis of L‐arginine to L‐ornithine is difficult to perform chemically, therefore the stabilization and immobilization of Bacillus subtilis arginase (EC 3.5.3.1) was studied in a continuously stirred membrane reactor system. Initial pH of the substrate solution, addition of L‐aspartic acid and reducing agents all appeared to have an effect on the operational stability of B. subtilis arginase. A remarkably good operational stability (total turnover number, TTN=1.13⋅108) at the pH of arginine free base (pH 11.0) was observed, which was further improved with the addition of sodium dithionite to the substrate solution (TTN>1⋅109). B. subtilis arginase was successfully immobilized on three commercially available epoxy‐activated supports. Immobilization on Sepabeads EC‐EP was most promising, resulting in a recovered activity of 75% and enhanced thermostability. In conclusion, the stabilization and immobilization of B. subtilis arginase has opened up possibilities for its application in the biobased production of nitrogen‐containing chemicals as an alternative to the petrochemical production.