Optimization of levan production by Zymomonas mobilis

Effect of different fermentation conditions on levan production by Zymomona s 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). Abov e 15% (20 and 25%) sucrose concentration, there was no increase in the biom ass. The sucrose hydrolysis and levan production occurred even in the absen ce of significant growth of cells. Maximum amount of levan was produced (14 .5 g/l) at pH 5 and 15 gn at 25 degrees C temperature. At temperature betwe en 35 degrees C and 40 degrees C, levan production was not detected. Presen ce of glucose in the medium considerably reduced levan production (2.8 g/l) than fructose 6.7 g/l.