Efficient reduction of 5-hydroxymethylfurfural to 2,5-bis(hydroxymethyl) furan by Bacillus subtilis HA70 whole cells

2,5-bis(hydroxymethyl)furan (BHMF) is an important reduction product from biomass-based 5-hydroxymethylfurfural (HMF), and microbial whole-cells are usually employed as the biocatalysts for HMF reduction. Due to the cell toxicity of HMF, the substrate loading was limited to a low concentration (100-200 mM). Herein, we isolated a highly HMF-tolerant strain, Bacillus subtilis HA70, as a whole-cell biocatalyst for the reduction of HMF. The strain exhibited high catalytic activity and excellent selectivity to HMF conversion, and the catalytic activity was significantly improved with the addition of glycine. Under the optimized conditions, 350 mM of HMF was transformed into BHMF with a yield of 91.2% and a selectivity of 99%. In the fed-batch conversion, 443.8 mM of BHMF was obtained within 15 h, giving a productivity of 29.6 mmol/(L h) and a total yield of 88.7%. Additionally, this strain also could selectively transform 100 mM of furfural into furfuryl alcohol with a yield of 97.6% within 4 h. The strong catalytic activity confers B. subtilis HA70 a promising potential for efficient synthesis of BHMF from HMF.