RESUMEN
The production of levan by Bacillus licheniformis NS032 in a medium based on sugar beet molasses was studied. High polysaccharide yields were produced by using diluted molasses (100-140â¯g/L of total sugars) with the addition of commercial sucrose up to 200â¯g/L of total sugars, as well as K2HPO4. A levan yield of 53.2â¯g/L was obtained on a medium optimized by response surface methodology, containing 62.6% of sugar originating from molasses, and 4.66â¯g/L of phosphate, with initial pH value of 7.2. In comparison to the media with 200 and 400â¯g/L sucrose, in the molasses optimized medium, the observed bacterial growth was faster, while the maximum production of polysaccharide was achieved over a shorter time interval (48â¯h). The polysaccharide produced in molasses medium had a weight average molecular weight of 5.82â¯×â¯106â¯Da, degree of branching 12.68%, viscosity of 0.24â¯dL/g, and based on methylation analysis and NMR data, it did not significantly differ from levan obtained in the medium with 200â¯g/L sucrose.