Characterization of a xylitol dehydrogenase from Aspergillus flavus and its application in l-xylulose production

Anurag Kumar; Jinglin Li; Sanath Kondaveeti; Bakul Singh; Ramasamy Shanmugam; Vipin Chandra Kalia; In-Won Kim; Jung-Kul Lee

doi:10.3389/fbioe.2022.1001726

Characterization of a xylitol dehydrogenase from Aspergillus flavus and its application in l-xylulose production

Front Bioeng Biotechnol. 2022 Sep 12:10:1001726. doi: 10.3389/fbioe.2022.1001726. eCollection 2022.

Authors

Anurag Kumar¹, Jinglin Li¹, Sanath Kondaveeti¹, Bakul Singh¹, Ramasamy Shanmugam¹, Vipin Chandra Kalia¹, In-Won Kim¹, Jung-Kul Lee¹

Affiliation

¹ Division of Chemical Engineering, Konkuk University, Seoul, South Korea.

Abstract

An NAD⁺-dependent xylitol dehydrogenase from A. flavus (AfXDH) was cloned and successfully expressed in Escherichia coli. AfXDH gene sequence revealed an open reading frame of 1,110 bp, encoding a polypeptide of 369 amino acids with a calculated molecular mass of 38,893 Da. Among various polyols, sorbitol and xylitol were preferred substrates of AfXDH with K_m values of 16.2 and 16.9 mM, respectively. AfXDH showed the highest activity in Tris-glycine-NaOH buffer (pH 9.5) at 50°C; it required Zn²⁺ or Mn²⁺ for enzyme activity. The half-life at 40°C and half denaturation temperature (T_1/2) was 200 min and 45°C, respectively. Bioinformatic analyses along with biochemical properties confirmed that AfXDH belonged to the medium-chain dehydrogenase/reductase family. AfXDH exhibits higher thermostability and k _cat values than those of other XDHs. The feasibility of using AfXDH in l-xylulose production was demonstrated. AfXDH, when coupled with Streptococcus pyogenes NADH oxidase, efficiently converted xylitol to l-xylulose with 97% yield, suggesting its usefulness for the industrial l-xylulose production from xylitol.

Keywords: Aspergillus flavus; L-xylulose; dehydrogenase; thermostability; xylitol.