Upgrading of furanic aldehydes to their corresponding furancarboxylic acids has received considerable interest recently. Herein we reported selective oxidation of furfural (FAL) to furoic acid (FA) with quantitative yield using whole-cells of Pseudomonas putida KT2440. The biocatalytic capacity could be substantially promoted through adding 5-hydroxymethylfurfural into media at the middle exponential growth phase. The reaction pH and cell dosage had notable impacts on both FA titer and selectivity. Based on the validation of key factors for FAL conversion, the capacity of P. putida KT2440 to produce FAL was substantially improved. In batch bioconversion, 170 mM FA was produced with selectivity nearly 100% in 2 h, whereas 204 mM FA was produced with selectivity above 97% in 3 h in fed-batch bioconversion. Particularly, the role of molybdate transporter in oxidation of FAL and 5-hydroxymethylfurfural was demonstrated for the first time. The furancarboxylic acids synthesis was repressed markedly by destroying molybdate transporter, which implied Mo-dependent enzyme/molybdoenzyme played pivotal role in such oxidation reactions. This research further highlights the potential of P. putida KT2440 as next generation industrial workhorse and provides a novel understanding of molybdoenzyme in oxidation of furanic aldehydes.

最近，将呋喃醛升级为其相应的呋喃羧酸引起了相当大的兴趣。在此，我们报道了使用全细胞将糠醛（FAL）选择性氧化为糠酸（FA），并定量产率恶臭假单胞菌KT2440。在指数生长期培养基中添加5-羟甲基糠醛可大幅提高生物催化能力。反应 pH 值和细胞剂量对 FA 滴度和选择性都有显着影响。基于对FAL转换关键因素的验证，恶臭假单胞菌KT2440生产FAL得到了大幅改进。在分批生物转化中，2 小时内产生的 170 mM FA 的选择性接近 100%，而在补料分批生物转化中，3 小时内产生的 204 mM FA 的选择性高于 97%。特别是，首次证明了钼酸盐转运蛋白在FAL和5-羟甲基糠醛氧化中的作用。通过破坏钼酸盐转运蛋白，呋喃甲酸的合成受到显着抑制，这表明钼依赖性酶/钼酶在此类氧化反应中发挥着关键作用。这项研究进一步凸显了恶臭假单胞菌KT2440 作为下一代工业主力，为呋喃醛氧化中的钼酶提供了新的理解。