Optimization of levan production by Zymomonas mobilis

Abstract

Effect of different fermentation conditions on levan production by Zymomonas mobilis B-4286 was studied. Levan production increased from 5.7-g/l to 12.6-g/l with an increase in initial sucrose concentration (50-150 g/l). Above 15% (20 and 25%) sucrose concentration, there was no increase in the biomass. The sucrose hydrolysis and levan production occurred even in the absence of significant growth of cells. Maximum amount of levan was produced (14.5 g/l) at pH 5 and 15 g /l at 25(0)C temperature. At temperature between 35(0)C and 40(0)C, levan production was not detected. Presence of glucose in the medium considerably reduced levan production (2.8 g/l) than fructose 6.7g/l.