Improved 5-hydroxymethyl-2-furfurylamine production from D-fructose-derived 5-hydroxymethylfurfural by a robust double mutant Aspergillus terreus ω-transaminase biocatalyst in a betaine-formic acid medium

5-Hydroxymethyl-2-furfurylamine (HMFA) as a key furan-based chemical is a useful intermediate, which is commonly used in the synthesis of drugs and can also be utilized as a curing agent in epoxy resins. In this work, a hybrid catalysis via chemoenzymatic approach was used to valorize D-fructose into HMFA. 5-Hydroxymethylfurfural (HMF) could be prepared in the yield of 72.1% via dehydration of D-fructose (54.0 g/L) in betaine-formic acid (5.0 wt%)−water for 90 min at 150 °C. Furthermore, HMFA was prepared from the prepared HMF by mutant transaminase biocatalyst. Site-directed mutagenesis of AT transaminase (derived from Aspergillus terreus) was performed through the mutation of histidine at position 210 and isoleucine at position 77 into asparagine and leucine, respectively. This double mutant HNIL with better thermal stability and higher substrate tolerance was obtained. Using the constructed recombination Escherichia coli HNIL whole-cell as biocatalyst, high titer of HMF (800 mM) was aminated to HMFA with D-alanine (amine donor) in the yield of 97.7 % at pH 8.0 and 35 °C. D-Fructose was efficiently converted into HMFA in a tandem reaction by bridging chemocatalysis with deep eutectic solvent Be-FA and biocatalysis with HNIL cell, reaching the yield of 0.46 kg HMFA per kg D-fructose (0.98 kg HMFA per kg HMF). This hybrid strategy provides a sustainable and efficient way for the chemoenzymatic catalysis of D-fructose for HMFA.