Biosynthesis of levan by levansucrase from Bacillus methylotrophicus SK 21.002

摘要

A new strain SK 21.002 which could produce intracellular levansucrase was isolated from beet sugar growing soil. It was identified as Bacillus methylotrophicus based on the sequence analysis of the 16S rRNA and the morphological characteristic. The structure of levan biosynthesized from the levansucrase was determined to be connected through 3-(2 ->6) linkages with fructofuranosyl residues. The molecular weight of the product was between 4 and 5 kDa. The optimal conditions to produce levan using the levansucrase were studied. The presence of Mg~(2+) could increase the yield of levan. The yield of levan reached about 100 g/L with the enzyme under the optimum conditions.