Optimization of medium for one-step fermentation of inulin extract from Jerusalem artichoke tubers using Paenibacillus polymyxa ZJ-9 to produce R,R-2,3-butanediol

The medium for one-step fermentation of raw inulin extract from Jerusalem artichoke tubers by Paenibacillus polymyxa ZJ-9 to produce R,R-2,3-butanediol (R,R-2,3-BD) was developed. Inulin, K2HPO4 and NH4Cl were found to be the key factors in the fermentation according to the results obtained from the Plackett–Burman experimental design. The optimal concentration range of the three factors was examined by the steepest ascent path, and their optimal concentration was further investigated according to the Box–Behnken design and determined to be 77.14 g/L, 3.09 g/L and 0.93 g/L, respectively. Under the optimal conditions, the concentration of the obtained R,R-2,3-BD was 36.92 g/L, at more than 98% optical purity. Compared with other investigated carbon resources, fermentation of the raw inulin extract afforded the highest yield of R,R-2,3-BD. This process featured one-step fermentation of inulin without further hydrolyzing, which greatly decreased the raw material cost and thus facilitated its practical application.