Efficient production of hydroxymethyl-2-furfurylamine by chemoenzymatic cascade catalysis of bread waste in a sustainable approach

In this study, efficient and sustainable conversion of waste bread (WB) to 5-hydroxymethyl-2-furoamine (HMFA) was achieved in a cascade reaction in betaine:malonic acid (B:MA) -water. 5-HMF (30.3 wt% yield) was synthesized from WB (40.0 g/L) in B:MA -water (B:MA, 18 wt%) in 45 min at 190( ?)C. By using the newly created recombinant E. coli HNILGD-AlaDH cells expressing L-alanine dehydrogenase (AlaDH) and ?-trans-aminase mutant HNILGD as biocatalyst, the WB-valorized 5-HMF was biologically aminated into HMFA in a high yield (92.1%) at 35( ?)C for 12 h through in situ removal of the amino transfer by-products of the amine donor, greatly reducing amine donor dosage (from D-Ala/5-HMF = 16/1 to D-Ala/5-HMF = 2/1, mol/mol) and improving the productivity of HMFA (0.282 g HMFA per g WB). This two-step chemical-enzymatic cascade reaction strategy with B:MA and HNILGD-AlaDH whole-cell provides a new idea for the chemoenzymatic syn-thesis of valuable furan chemicals from waste biomass.