Identification of a Novel Dehydrogenase from Gluconobacter oxydans for Degradation of Inhibitors Derived from Lignocellulosic Biomass

Inhibitors from lignocellulosic biomass have become the bottleneck of biorefinery development.Gluconobacter oxydansDSM2003 showed a high performance of inhibitors degradation, which had a short lag time in non-detoxified corn stover hydrolysate and could convert 90% of aldehyde inhibitors to weaker toxic acids. In this study, an aldehyde dehydrogenase geneW826-RS0111485, which plays an important function in the conversion of aldehyde inhibitors inGluconobacter oxydansDSM2003, was identified.W826-RS0111485was found by protein profiling, then a series of enzymatic properties were determined and were heterologously expressed inE. coli. The results indicated that NADP is the most suitable cofactor of the enzyme when aldehyde inhibitor is the substrate, and it had the highest oxidation activity to furfural among several aldehyde inhibitors. Under the optimal reaction conditions (50 °C, pH 7.5), theKmandVmaxof the enzyme under furfural stress were 2.45 and 80.97, respectively, and theKcatwas 232.22 min−1. The biodetoxification performance experiments showed that the recombinantE. colicontaining the target gene completely converted 1 g/L furfural to furoic acid within 8 h, while the controlE. colionly converted 18% furfural within 8 h. It was further demonstrated thatW826-RS0111485played an important role in the detoxification of furfural. The mining of this inhibitor degradation gene could provide a theoretical basis for rational modification of industrial strains to enhance its capacity of inhibitor degradation in the future.Keywords:inhibitors degradation;Gluconobacter oxydans;protein profiling;aldehyde dehydrogenase;furfural