Inhibition By Toxic Compounds In The Hemicellulosic Hydrolysates On The Activity Of Xylose Reductase From Candida Tropicalis

Xylose reductase (XR) is an oxidoreductase
having potential applications in the production of
various specialty products, mainly xylitol. It is
important to screen for compounds that can decrease
XR activity and consequently can decrease xylitol
production. We have identified the byproducts in the
hemicellulosic hydrolysate that inhibit XR from
Candida tropicalis and measured their effects. XR
inhibitory activities of byproducts, glucose, acetic
acid, arabinose, lignin-degradation products (LDPs),
furfural and hydroxymethylfurfural (HMF), were
evaluated by measuring the MIC and IC50 values.
XR activity was 11.2 U/ml. Acetic acid, LDPs,
furfural and HMF significantly inhibited XR with
IC50 values of 11, 6.4, 2.3 and 0.4 g/l, respectively.
This is the first report on the inhibitory activities of
several byproducts for XR.