Oxygen transfer and uptake rates during xanthan gum production

Oxygen uptake rate and oxygen mass transfer rate have been studied during x anthan gum production process in stirred tank bioreactor. Empirical equatio ns for the oxygen mass transfer coefficient have been obtained taking into account several variables such as air how rate, stirrer speed and apparent viscosity. Oxygen uptake rate evolution in the course fermentation has been measured, obtaining an equation as a function of biomass concentration, in cluding overall growth and non growth-associated oxygen uptake. A metabolic kinetic model has been employed for xanthan gum production description inc luding oxygen mass transfer and uptake rates. The results point out that th is model is able to describe adequately not only oxygen dissolved evolution , but. also of the production of xanthan and substrate consumption. Also, t he influence of several parameters (k(L)a, air flow rate and dissolved oxyg en) in the evolution of the key compounds of the system have been studied. The results of the simulation shown that an increasing of dissolved oxygen concentration favor the xanthan gum production. (C) 2000 Elsevier Science I nc. All rights reserved.