中国生物工程杂志

Permeabilized cells containing trehalose synthase from Meiothermus sp. CBS-01 was immobilized by the integration of entrapment in alginate beads with cross-linking and electrostatic self-assembly coating technique. Coating on alginate beads with diazo-resin and poly(styrene sulfonate) can protect the beads from degradation in phosphate buffer, whereas cross-linking with carbodiimide improves the thermostability of trehalose synthase entrapped in alginate beads. By co-immobilization of permeabilized cells using entrapment-cross-linking- coating method, the enzyme recovery was 32%, and the optimum temperature of the enzyme was still 60℃, but the optimum pH was shifted from 6.5 to 7. In batch manner, a maximum conversion yield of 60% trehalose from maltose could be reached by the immobilized cells. Within 4 times repeated use of the immobilized cells, and each time was operated at 50℃ for 24h, more than 50% conversion yield of trehalose could be maintained with less than 20% loss of the enzyme activity.