Characterization of xanthan gum biosynthesis in a centrifugal, packed-bed reactor using metabolic flux analysis

Abstract

Xanthan gum biosynthesis in a centrifugal, packed-bed reactor (CPBR) was characterized using metabolic flux analysis. Metabolic fluxes through the carbon pathways for xanthan gum production by Xanthomonas campestris were calculated by the metabolic flux-based stoichiometric model. Use of 5.0% instead of 2.5% glucose resulted in an enhanced glucose uptake rate (ν s) in all bioreactors. The ν s values in CPBR were significantly higher than those in STR, as were the assembling rate (ν 1) of sugar nucleotides transformed from Glc-6-P. However, the highest ratio of ν 1/ν 2 was found in CPBR-LC with 5.0% glucose, indicating that most glucose was utilized for xanthan synthesis with the minimum maintenance requirements in the CPBR-LC operation. Despite the high xanthan productivity and glucose uptake achieved in CPBR-GC, CPBR-LC with 5.0% initial glucose concentration was the most energy-efficient operation among all systems studied.