초록
<P><B>Abstract</B></P> <P>A novel fermenter system utilising immobilised <I>Rhizopus oryzae</I> 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 0.75gg<SUP>−1</SUP> achieved for the DO 60% and 80% fermentations.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Three distinct production phases were observed. </LI> <LI> ATP production from respiration had an upper bound–2mmol ATPgbiomass<SUP>−1</SUP> h<SUP>−1</SUP>. </LI> <LI> Instantaneous fumarate yield highest when ethanol flux terminates. </LI> <LI> Higher DO and pH mitigated fumarate flux inhibition after ethanol flux termination. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>