Synthesis Of Furfuryl Alcohol And 2,5-dihydroxymethylfuran From Biomass Via Tandem Catalysis With Deep Eutectic Solvent And Reductase

Furfural(FAL)and 5-hydroxymethylfurfural(HMF)can be used as substitutes for petroleum-based precursors in a wide range of industries such as chemicals,food,pharmaceuticals,biofuels,adhesives and solvents.Furfuryl alcohol(FOL)is an important furfural upgrading compound used primarily in the production of tartaric acid,resins,additives,polymers,fibers,and rocket fuel.2,5-Dihydroxymethylfuran(BHMF)is a downstream product of 5-hydroxymethylfurfural and is a versatile building block used in the synthesis of polymers,fuels,and macrocyclic polyethers.Currently,most manufacturers use conventional chemical catalysts to produce furan alcohols.But it usually requires strong acids and bases or high temperature and pressure and other more stringent reaction conditions.In this study,the betaine-based deep eutectic solvent(DES)was used as the chemocatalysts and newly constructed recombinant E.coli SF21 containing aldehyde reductase and formate dehydrogenase(FDH)was used as the biocatalyst,the synthesis of agricultural waste(corncob,bagasse)into furanol via tandem chemoenzymatic catalysis in one-pot manner.The results were obtained as follow:Firstly,betaine and citric acid(CA)were mixed to prepare deep eutectic solvent CA:Betaine.Using CA:Betaine(10 wt%)as a catalyst and reaction medium,carbohydrates(glucan plus xylan)from corncob(60 g/L)were catalyzed to produce 74.6 m M furfural,96.5m M formic acid,and 40.3 m M glucose in the CA:Betaine-Water(10:90,wt:wt)system at 170℃ for 30 min.Using CA:Betaine(8 wt%)as a catalyst and reaction medium,carbohydrates from bagasse(40 g/L)were catalyzed to produce 47.9 m M 5-hydroxymethylfurfural,14.0m M furfural,62.9 m M formic acid,and 3.9 m M glucose in the CA:Betaine-water(8:92,wt:wt)system at 170 ℃ for 30 min.This showed that this DES could effectively prepare furan aldehydes(FAL,5-HMF)using biomass as raw material.Secondly,E.coli SF21 containing formate dehydrogenase(FDH)and NADPH-dependent aldehyde reductase(Ss CR)was constructed.FDH can catalyze biomass-derived formate,converting them into carbon dioxide while providing NAD(P)H to biologically convert the biomass-derived furfural and 5-hydroxymethylfurfural into furfuryl alcohol and 2,5-dihydroxymethylfuran,respectively.Under the same conditions,recombinant E.coli SF21 exhibited higher activity and productivity compared to E.coli CCZU-A13 containing only the Ss CR gene,based on the concentrations of various products in the dilute solution of furfural derived from corncob.This also suggested that co-expression of FDH and NAD(P)H-dependent aldehyde reductase(Ss CR)in E.coli was a good strategy for efficient biotransformation of furan alcohols.Finally,using deep eutectic solvent CA:Betaine catalyst and recombinant E.coli SF21whole-cell biocatalyst,one sustainable way for valorisation of biomass into value added furnan alcohols was developed via chemoenzymatic conversion in one-pot manner.In 2 h,SF21 whole cell used corncob-derived formic acid and glucose as co-substrates,and effectively converted derived furfural(74.6 m M)to furfuryl alcohol(95.8% yield),reaching a furfuryl alcohol productivity of 0.117 g/g corncob(0.343 g/g xylan).In 6 h,5-hydroxymethylfurfural(47.9 m M)and furfural(14.0 m M)derived from bagasse were also effectively converted to 2,5-dihydroxymethylfuran and furfuryl alcohol.The productivity of2,5-dihydroxymethylfuran reached 0.137 g furfuryl alcohol/g bagasse(0.323 g2,5-dihydroxymethylfuran/g glucan),and furfuryl alcohol productivity reached 0.033 g furfuryl alcohol/g bagasse(0.136 g furfuryl alcohol/g xylan).This demonstrated the feasibility of catalyzing the synthesis of agricultural wastes into furan alcohols via tandem chemoenzymatic method.Overall,this study had developed via chemoenzymatic conversion in one-pot manner to efficiently transform biomass into 2,5-dihydroxymethylfuran and furfuryl alcohol.Corncob and bagasse were catalyzed to 5-hydroxymethylfurfural and furfural by an efficient and biocompatible betaine-based deep eutectic solvent.Then recombinant E.coli SF21whole-cell efficiently catalyzed 5-hydroxymethylfurfural and furfural into2,5-dihydroxymethylfuran and furfuryl alcohol.An efficient process for the synthesis of funan alcohols under benign and green conditions was established,and provided a new idea for the sustainable conversion of biomass into furan alcohols.