Enhanced Biosynthesis of _D-Arabitol by Metschnikowia reukaufii Through Optimizing Medium Composition and Fermentation...

_D-Arabitol is an important functional sugar alcohol, which can be used in the preparation of foods, chemicals, and medicines. Despite biological production of _D-arabitol from low-cost substrates has recently been the focus of research, low yield of this technology has limited its large-scale exploitation. Optimization of this bioprocess could be a promising option to improve the yield of _D-arabitol. In this study, one-factor-at-a-time (OFAT) strategy and Box-Behnken design (BBD) were used to increase _D-arabitol production by Metschnikowia reukaufii CICC 31,858 through optimizing the fermentation conditions and medium composition. The OFAT optimization provided the optimal conditions for temperature, agitation speed, and fermentation time of 30℃, 220 rpm, and 6 days, respectively. Likewise, the optimum concentrations of peptone, ammonium sulfate, KH₂PO₄, MgSO₄·7H₂O, and fumaric acid in the fermentation medium were (g/L) 7.5, 1, 2, 0.5, and 7.5, respectively. Under these optimum conditions, 80.43 g/L of _D-arabitol was produced from 200 g/L of glucose, with a productivity of 0.56 g/L/h. The BBD optimization with three important components of fermentation medium (KH₂PO₄, MgSO₄·7H₂O, and fumaric acid) showed that the predicted titer of _D-arabitol varied from 47.21 to 89.27 g/L, and the actual titer of _D-arabitol ranged from 47.36 to 89.83 g/L. The optimum concentrations (g/L) of KH₂PO₄, MgSO₄·7H₂O, and fumaric acid in the fermentation medium were found to be 1.0, 0.5, and 4.7 g/L, respectively. Under the optimum conditions, 92.45 g/L of _D-arabitol was finally produced with the yield and productivity of 0.46 g/g and 0.64 g/L/h, respectively.