Evaluation of Specific Oxygen Uptake Rates with Reference to Biocatalytic D-Sorbitol Oxidation Systems
Krešo Mihaljević1* and Marijan Bošnjak2
1PLIVA d.d., Fine Chemicals, Prilaz baruna Filipovića 25, HR-10 000 Zagreb, Croatia
2Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, HR-10 000 Zagreb, Croatia
Article history:
Received: April 16, 2003
Accepted: June 9, 2003
Key words:
D-sorbitol microbial oxidation, oxygen uptake, D-sorbitol concentration effects, process relationships
Summary:
Effects of D-sorbitol concentration on the kinetics of D-sorbitol microbial oxidation were studied. The culture of Gluconobacter suboxydans S–22 was applied as a biocatalyst. The study was focused on the determination of oxygen uptake rates and the evaluation of factors affecting them. Special emphasis was given to estimations of dissolved oxygen saturation (Monod) constant (KsDO) and critical dissolved oxygen concentration. The estimated values of Monod constant (KsDO) were correlated with different process kinetics parameters and a series of acceptable relationships was established. Excellent correlation coefficients were found for KsDO as a linear function of (i) reciprocal viscosity (R2 = 0.9848), (ii) relative diffusion coefficient (R2 = 0.9983), (iii) cubic root of dissolved D-sorbitol mass concentration (R2 = 0.9915) and (iv) oxygen solubility in D-sorbitol solutions of different D-sorbitol concentrations (R2 = 0.9967). The estimated KsDO values were lower than their corresponding critical dissolved oxygen concentrations.
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