Effect of furfural addition on xylose utilization by Kluyveromyces marxianus IMB4 under anaerobic and microaerobic conditions

The study focuses on the effect of furfural during xylose fermentation by Kluyveromyces marxianus IMB4. Furfural, a degradation product formed during lignocellulose pretreatment, acts as a terminal electron acceptor for the regeneration of NAD⁺, thereby increasing ethanol yield. We investigated three levels of furfural concentration (0, 0.5, and 1 g L ^-1) under anaerobic and microaerobic fermentation conditions. The concentrations of xylitol produced were higher compared to ethanol under both fermentation conditions. Significant amounts of acetic acid were also produced under all fermentation conditions. The maximum ethanol produced under anaerobic conditions was 1.38 g L^-1 with 1.0 g L^-1 added furfural, while a maximum xylitol of 9.61 g L^-1 was produced in the control treatment. Under microaerobic fermentation conditions, maximum ethanol of 2.07 g L^-1 was produced with 1.0 g L^-1 added furfural, while maximum xylitol of 4.41 g L^-1 was produced in the control treatment. These results indicate that the addition of furfural did not significantly improve ethanol production or inhibit xylitol production.