Chiang Mai Journal of Science

Escherichia coli Top-10 containing a levansucrase gene (lsRN) of Bacillus licheniformis RN-01, cultivated in 3X LB medium, produced levansucrase at 65.7 U/ml of culture medium. The purified levansucrase had a MW of 52 kDa and specific activity of 170.04 U/mg protein with 6.6 purification fold and 62.2% yield. B. licheniformis RN-01 levansucrase was covalently bound on chitosan beads, Sepabead EC-EP beads, and Sepabead EC-HFA beads with the immobilization efficiency of 96%, 35%, and 23%, respectively. Levansucrase immobilized on chitosan beads retained over 75% of its activity after 10 cycles of repetitive use. In contrast, levansucrase immobilized on Sepabead EC-EP or Sepabead EC-HFA lost over 60% after only 5 cycles of repetitive used.  The optimum pH and temperature of the immobilized enzyme on chitosan beads (pH 4.0-6.0, 40-50^oC) were significantly broader than those of the free enzyme (pH 6.0, 50^oC). These results demonstrated that chitosan beads have superb characteristics for levansucrase immobilization.