Production of recombinant choline oxidase and its application in betaine production

The paper describes the author’s successful work to express and use recombinant choline oxidase. The gene for the choline oxidase was isolated from a Gram-positive soil bacterium, cloned into an expression vector, inserted into and overexpressed in a Rosetta expression system. The isolated recombinant choline oxidase was subsequently immobilized onto Ni-Sepharose beads, which were loaded in a rotating bed reactor (RBR). With the immobilized choline oxidase in the RBR, reaction conditions such as pH and temperature were optimized and the enzymatic activity measured for the reaction of choline to glycine betaine via betaine aldehyde.

Highlights:

• "The purified 8000 units of choline oxidase enzyme was immobilized to 20 mL of Ni-Sepharose resin and placed inside the rotating cylinder of SpinChem Rotating Bed Reactor (RBR). The RBR was placed in a 500 mL vessel containing 13.9 g of choline chloride dissolved in the 100 mL of 10 mM Tris-HCl buffer (pH 8.0). 600 units of catalase was added to the enzymatic reaction and RBR was spun at 100 rpm at 37 °C for 12 h."
• "The enzymatically produced betaine was estimated by the formation of betaine reineckate and we were able to produce 0.83 molar of betaine from one molar of choline chloride."