Naude, AndreNicol, Willie2017-06-282017-05Naude, A. & Nicol, W. 2017, 'Fumaric acid fermentation with immobilised Rhizopus oryzae : quantifying time-dependent variations in catabolic flux', Process Biochemistry, vol. 56, pp. 8-20.1359-5113 (online)1873-3298 (print)10.1016/j.procbio.2017.02.027http://hdl.handle.net/2263/61170A novel fermenter system utilising immobilised Rhizopus oryzae is presented. The impact of dissolved oxygen (20%, 60% and 80%) and pH (4 and 5) was investigated. All fermentations exhibited three distinct phases. Phase A, at the start, was associated with no fumarate production, minimal respiration and ethanol as the major product. Phase B was characterised by the onset of fumarate production and significant ethanol and respiration fluxes. Phase C was associated with zero ethanol flux. Inhibition of fumarate production was more severe at low pH. The DO 20% fermentation (pH 5) had a low respiration flux which resulted in excessive ethanol production. Higher DO levels resulted in less inhibition of fumarate production during phase C. Instantaneous fumarate yields on glucose were at a maximum at the start of phase C, with values in excess of 0.75 gg(-1) achieved for the DO 60% and 80% fermentations.English© 2017 Elsevier Ltd. All rights reserved. Notice : this is the author's version of a work that was accepted for publication in Process Biochemistry resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. A definitive version was subsequently published in Process Biochemistry, vol. 56, pp. 8-20, 2017. doi : 10.1016/j.procbio.2017.02.027.Fumaric acidFermentationImmobilizationBioreactorsRhizopus oryzaePostprint Article