Extracellular secretion of levansucrase from Zymomonas mobilis in Escherichia coli

Secretion of levansucrase from Zymomonas mobilis in Escherichia coli by gly cine supplement was investigated. A significant amount of levansucrase (abo ut 25% of total activity) was found in intact whole-cells. Cell fractionati on experiments showed that levansucrase was found both in the periplasmic s pace and in the cytoplasmic fraction of E. coli. None or only trace amounts of levansucrase was detected in the extracellular culture broth at 24 h of cultivation and it accrued with the increasing concentration of glycine in the culture medium and duration of the culture period. Optimal glycine con centration for the maximum secretion of levansucrase was in the range of 0. 8-1%, in which approximately 20-50% of levansucrase was released into the e xtracellular fraction at 24 h of cultivation, although glycine retarded the bacterial growth.