Monday, April 30, 2007

Optimization of xanthan production by Xanthomonas campestris grown in coconut juice

Sasithorn Kongruang, Division of Biotechnology, Department of Agro-Industrial Technology, Faculty of Applied Science, King Mongkut’s Institute of Technology North Bangkok, 1518 Piboonsongkram Road, Bangsue, Bangkok, Thailand

The exopolysaccharide from Xanthomonas campestris is one of the major commercial biopolymers and other industrial applications such as pharmaceuticals, agriculture, textile and petroleum production. Xanthan gum production by Xanthomonas campestris TISTR 1100  using coconut juice as carbon source was studied. Batch fermentations were experimented under 33 0C with an agitation rate of 700 rpm. The supplementation of the medium were investigated in order to improve xanthan gum production. K2HPO4 addition to the medium had a significant positive effect on both xanthan gum and biomass production (p =0.001 and p=0.010). Maximum specific rates of growth , xanthan production, and overall carbon yield relative to sucrose consumption during the growth of Xanthomonas campestris in supplemented coconut juice were compared with those of non-supplementation.An increasing of carbon conversion into xanthan was observed throughout the fermentation times. Xanthan yields approximately 60% g/g were obtained with constant acetyl content. Result showed the pyruvyl subtitution decreased as the growth rate gradually reduced. However, the yeast extract , NH4Cl and NaNO3 addition only promoted biomass production. The fermentation kinetics were also reported.