Construction of a dual-enzyme cascade bioreaction system for sustainable biotransformation of hemicellulose-derived furfural to furfurylamine

In recent years, biocatalytic technology has shown great potential in the synthesis of furan compounds. As an important derivative of furan compounds, furfurylamine is widely used in chemical industry, medicine, agriculture, food and other fields. It can be used to manufacture fuel synergists, functional fibers, pharmaceutical intermediates, polymer materials and so on. In this study, a dual-enzyme co-expression recombinant E. coli HN-AlaDH system was innovatively constructed by expressing Aspergillus terreus mutant-transaminase (HN210, His→Asn at position 210) and Bacillus subtilis L -alanine dehydrogenase (AlaDH). By optimizing the double enzyme expression system, the D -alanine-NH 4 Cl mixed amine donor was innovatively used, and the amount of D -alanine was reduced, which not only effectively inhibited the accumulation of pyruvic acid, but also significantly improved the catalytic efficiency. By optimizing the reaction conditions (40 °C, pH 7.5) and implementing the fed-batch strategy, the efficient conversion of 200 mM furfural was achieved within 16 h, and the final product yield was 92.6 %. The study further developed an integrated chemobiological cascade catalytic process: Firstly, Choline chloride/Malonic acid/Malic acid ternary deep eutectic solvent (20 wt%) was used to catalyze the dehydration of biomass-derived D -xylose to furfural. Subsequently, in the same reaction system, D -xylose-derived furfural was converted into the target product through the catalysis with recombinant E. coli HN-AlaDH, and the overall conversion efficiency was as high as 94.5 % (based on the furfural loading). This innovative tandem catalytic strategy not only simplified the process flow, but also significantly improved the reaction efficiency, which provided a new idea for the green manufacturing of bio-based chemicals. The research results show the great potential of biocatalysis technology in sustainable chemical synthesis and provide important technical support for the green development of related industries. • E. coli HN-AlaDH expressed L -alanine dehydrogenase and ω-transaminase mutant HN. • Mixed amine donors ( D -Ala/NH 4 Cl/FAL=6/0.25/1) favored furfural (FAL) bioamination. • ChCl/MA/MaA (20 wt%) was used to catalyze D -xylose (300 mM) to FAL. • Chemobiological method was established to convert D -xylose into furfurylamine (FLA).