| abstract |
Cells having enzyme activity, and the enzyme activity thereof, are preserved for a prolonged period of time, as a suspension of microbial cells or as a suspension of immobilized cells in particles, in an aqueous medium that is a neutral or weakly basic aqueous solution of inorganic salts, having a molarity ranging from 100 mM to the saturation concentration of the inorganic salts. Preferably, the microbial cells are cells containing the enzyme, nitrile hydratase or nitrilase, such as Gordona terrae or Rhodococcus rhodochrous, and the inorganic salts are phosphates, borates, sulfates, sulfites or hydrochlorides. The present invention provides an industrially useful method for preserving a large quantity of cells or immobilized cells in particles having nitrile hydratase or nitrilase enzyme activity for a prolonged period of time (e.g., 300 days) without cell lysis or enzyme deterioration even at room temperature. The present invention also renders possible a sharp reduction in labor and cooling cost, which are necessary in the conventional preservation process. |