Molecular cloning and expression in Escherichia coli of an exo-levanase gene from the endophytic bacterium Gluconacetobacter diazotrophicus SRT4.

Gluconacetobacter diazotrophicus produces levan from sucrose by a secreted levansucrase (LsdA). A levanase-encoding gene ( lsdB), starting 51 bp downstream of the lsdA gene, was cloned from strain SRT4. The lsdB gene (1605 bp) encodes a protein (calculated molecular mass 58.