Most polymer-produced microorganisms are either aerobes or facultative anaerobes, so normally, viscosity affect the dissolved oxygen value of culture media is an essential requirement for polymer production (Sutherland, 1990). Oxygen is usually needed for the polymer synthesis or for the oxidation of reduced pyridine nucleotides that have been generated (Margaritis and Pace, 1985). As the viscosity of the medium increases with polymer formation, oxygen transfer to the cells becomes decrease. The exopolysaccharide production by Agrobacterium tumefaciens ID 95-748 was strongly inhibited by oxygen limitation, polymer yield decreased from 9.40 to 2.06 g/l as the cultivation volume in shake flaske (250 ml) increased (Stredensky et al, 1999)