Characterization of the Furfural and 5-Hydroxymethylfurfural (HMF) Metabolic Pathway in the Novel Isolate Pseudomonas...

The genes involved in the aerobic bacterial metabolism of furfural and 5-hydroxymethylfurfural (HMF) have been characterized in two species, Pseudomonas putida Fu1 and Cupriavidus basilensis HMF14. A third furan-metabolizing strain, Pseudomonas putida ALS1267, was recently identified that grows robustly on both furfural and HMF as sole carbon sources, with a growth rate of 0.250 h^-1 on furfural and 0.311 h^-1 on HMF, and we have characterized the genes involved in furfural and HMF metabolism in this bacterium. Unlike C. basilensis HMF14, which contains separate furfural and HMF operons, P. putida ALS1267 contains one contiguous 18.1-kb operon, which harbors all of the furfural- and HMF-metabolizing genes except for one, the hmfH gene that encodes HMF/furfural oxidoreductase and has both HMF acid oxidase and furfural/HMF dehydrogenase activity. The 18.1-kb operon was cloned into P. putida KT2440, which cannot metabolize furans, enabling growth on furfural as the sole carbon source with a growth rate of 0.340 h^-1. The clone did not allow P. putida KT2440 to metabolize HMF, most likely due to the lack of the hmfH gene. No hmfH homolog was identified in P. putida ALS1267, suggesting that another gene in the ALS1267 genome provides this function.