Biosynthesis of 5-hydroxymethyl-2-furancarboxylic acid from 5-hydroxymethylfurfural via new whole-cell biocatalysts.

The selective oxidation of biomass-derived 5-hydroxymethylfurfural (HMF) to value-added furan compounds presents significant challenges due to the inherent high reactivity of HMF. In this study, two microorganisms were identified as whole-cell biocatalysts for the synthesis of 5-hydroxymethylfuroic acid (HMFCA) from HMF. The cells of Pseudochrobactrum sp. B2L and Lysinibacillus sp. B2P showed susceptibility to low pH conditions that result from the accumulation of the HMFCA product. Nevertheless, they exhibited high tolerance to the HMF substrate and the 2,5-bis(hydroxymethyl)furan (BHMF) intermediate during the reaction process. Under optimized conditions, a concentration of 200 mM HMF was nearly completely converted into HMFCA, achieving a yield of 99% by utilizing the cells of both microorganisms. Upon increasing the HMF substrate concentration to 300 mM, HMFCA yields of up to 80% were obtained, demonstrating excellent catalytic performance. The identification of Pseudochrobactrum sp. B2L and Lysinibacillus sp. B2P as biocatalysts for the synthesis of HMFCA expands the biocatalytic repertoire available for the sustainable production of bio-based chemicals from HMF. Furthermore, these findings contribute valuable insights for the future identification of related enzymes.