Enhanced xanthan production process in shake flasks and pilot scale bioreactors using industrial semidefined medium

Abstract

Xanthan gum, a heteropolysaccharide produced by Xanthomonas campasteris, is a widely used biopolymer in food industries. The production process is highly influenced by the type and concentration of the different carbon and nitrogen source as well as other medium components. The
aim of this work was to develop an economic industrial medium for industrial production. In shake flask level, the maximal production of xanthan of 19.9 gL-1 was achieved by excluding ammonium nitrate from
the industrial medium and making new medium formulation composed of (sucrose, soybean meal, ammonium phosphate and magnesium sulphate). Further optimization in the production process was achieved by transferring the process to 16-L bioreactor and cultivation under controlled pH condition. The maximal volumetric and specific xanthan production [YP/X] obtained were 28 gL-1 and 11.06 g g-1, respectively. Thus, the semi-defined medium formulation developed in this work could be better and alternatively used for large scale production process for xanthan production when compared to other published media in respect to yield and cost.

Key words: Xanthan gum, Xanthomonas campestris, batch culture, semi-defined medium, biopolymer.