Xanthan production by Xanthomonas campestris in continuous fermentation

Abstract

Xanthan production by a strain of X. campestris was maintained longer under glucose-limited than nitrogen-limited conditions in continuous culture. The turnover Q was 12 at lower pH(5.0-6.0) and 6.5 at neutral pH; xanthan productivity was comparable at both pH in nitrogen-limited continuous cultures. In the Fe-rich continuous fermentation cell degeneration did not occur for 65 turnovers whereas in the Fe-deficient fermentation it occurred in 12 turnovers. The culture stability for xanthan formation is higher under conditions which are favorable for cell growth with limited xanthan production.