Bioprocess optimization of Xanthan production by Xanthomonas campestris using semi-defined medium in batch and fed-batch culture

Xanthan gum is an extracellular hetero polysaccharides of many industrial applications and produced by Xanthomonas campestris. This biopolymer is produced as extracellular product in submerged fermentation system. The production of xanthan was influenced by the concentration in glucose in medium. The maximal volumetric production of 17.9 g L was obtained in 80 g L glucose culture in shake flask level. Furthermore, cultivations were carried out in in situ sterilizable 15-L pilot scale bioreactor to improve this cultivation process. Using batch cultivation mode, the maximal xanthan production of 28.5 g L was obtained after 60 h cultivation. Based on data of batch culture, fed-batch cultivation with increased feeding rate using either glucose or complete medium as feeding solution was developed. The results clearly showed that, fed-batch cultivation using complete medium solution (chemically defined medium supplemented with glucose), increased volumetric xanthan production up to 43.15 g L (about 51% higher than the corresponding batch culture) but with almost the same value of specific production of about 6.35 g g. Thus, fed-batch cultivation mode using completely defined medium could be good alternative for economic production of xanthan in industrial scale.