Xanthan production in stirred tank fermenters: Oxygen transfer and scale‐up

Abstract

Abstract The microbial polysaccharide xanthan was produced by cultivation of Xanthomonas campestris in four stirred tanks with volumes ranging from 0.072 to 3 m 3 . Many of the previously suggested correlations for the volumetric mass transfer coefficient described the present data very unsatisfactorily. When Rushton turbines were employed as stirrers, the experimental results agreed well with a correlation suggested by Kawase and Moo‐Young; for the more energy‐efficient INTERMIG impellers, this correlation was modified by a factor of three. Constant specific oxygen transfer rate was found to be the appropriate scale‐up criterion for constant space‐time yield and constant product quality, specifically, the molar mass which determines the viscosity yield.