Poster Presentation 1B-44

Oxidation of Glucose to Gluconic Acid by Glucoseoxidase

in Membrane Bioreactor

Ester Junko Tomotani, Luiz Carlos Martins das Neves and Michele Vitolo*

University of São Paulo

School of Pharmaceutical Sciences

Department of Biochemical and Pharmaceutical Technology

Av. Prof. Lineu Prestes, 580, B-16, 05508-900

São Paulo, SP, Brazil

Phone: 55-11-30913862

Fax: 55-11-38156386

E-mail: michenzi@usp.br

Gluconic acid (GA) is commonly produced in industry through the fermentation of glucose by Aspergillus niger. However, using glucose oxidase (GO) instead of cells, the overall bioconversion process could be simplified by eliminating the fermentation disadvantages (cell separation, by-products formation, and the discharge of huge amounts of potential pollutant residues, among others). In this work, glucoseoxidase (SIGMA^® , G-6766) was used as catalyst for oxidizing glucose into GA, using a 10mL-BIOENGINEERING MEMBRANE REACTOR^® coupled with a Millipore® UF- polyethersulfone-membrane (cut off 100kDa) and operated by 12h under agitation of 300rpm, pH 5.5 and 30^oC. The effect of feeding rate (0.10 or 0.15 min^-1), glucose (2.5 or 5.0mM) and GO (1.0 or 2.0 mg/mL) concentrations on the catalysis were studied. A GA yield of about 55% was attained, when the bioreactor filled with 1.0 mg/mL of GO was fed up with 2.5mM glucose solution at a feeding rate of 0.15 min^-1. A higher yield could probably be attained, if the reversible non competitive inhibitory effect (K_i= 1.12 mM) promoted by H₂O₂ (the reaction co-product) was erased, by adding a peroxide decomposing agent (catalase, for instance).