Mechanism of furfural inhibition

• Furfural is metabolized by S. cerevisae under aerobic, oxygen-limited, and anareobic conditions to furfural alcohol.
  –Furfural reduce the specific growth rate, the cell-mass yield on ATP, the volumetric, and specific ethanol production
  –NADH-dependent yeast alcohol dehydrogenase (ADH) is believe to be responsible for furfural reduction.
  –Under anaerobic conditions, glycerol is normally produced to regenerate excess NADH formed in biosynthesis. Glycerol production reduction during furfural reduction suggests that furfural reduction regenerates NAD+.
  –Elevated concentrations of acetaldehyde excreted in the beginning of the fermentation, which was suggested to be due to a decreased NADH concentration in the cell during furfural reduction.
  –Furfural inhibition of glycolytic enzymes in vitro and the direct inhibition of ADH might have contributed to acetaldehyde excretion.
  –Intracellular acetaldehyde acumination suggested to be the reason for lag-phase in growth in the presence of furfural.
  –The model
  »i) furfural reduction to furfural alcohol by NADH dependent dehydrogenases had a higher priority than reduction of dihydroxyacetone phosphate to glycerol
  »ii) furfural caused inactivation of cell replication.