Production of levan by Bacillus licheniformis NS032 in sugar beet molasses-based medium.

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 (100-140 g/L of total sugars) with the addition of commercial sucrose up to 200 g/L of total sugars, as well as K2HPO4. A levan yield of 53.2 g/L was obtained on a medium optimized by response surface methodology, containing 62.6% of sugar originating from molasses, and 4.66 g/L of phosphate, with initial pH value of 7.2. In comparison to the media with 200 and 400 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 (48 h). The polysaccharide produced in molasses medium had a weight average molecular weight of 5.82 × 106 Da, degree of branching 12.68%, viscosity of 0.24 dL/g, and based on methylation analysis and NMR data, it did not significantly differ from levan obtained in the medium with 200 g/L sucrose.

Steroidal geminal dihydroperoxides and 1,2,4,5-tetraoxanes: structure determination and their antimalarial activity.

Cholestane-derived gem-dihydroperoxides and tetraoxanes were synthesized starting from 5 alpha- and 5 beta-cholestan-3-ones by acid-catalyzed addition of hydrogen peroxide to the ketone. They were characterized by IR, NMR, and mass spectroscopy analysis aided by molecular mechanics calculations, and, in the instance of 5 beta-cholestane-3 alpha,3 beta-dihydroperoxide (6), by x-ray analysis. The synthesized compounds were tested in vitro against Plasmodium falciparum Sierra Leone (D6) and Indochina (W2) malaria clones. All compounds were inactive to both clones, with the exception of tetraoxane 7a, which exhibited modest activity toward D6 clone with IC50 = 155 nM.