Optimization of fermentation medium for a newly isolated yeast strain (Zygosaccharomyces rouxii JM-C46) and evaluation of factors affecting biosynthesis of D-arabitol

A newly isolated yeast strain, namely Zygosaccharomyces rouxii JM-C46, was reported to be promising for enhanced D-arabitol production from glucose. In this study, further efforts were made to optimize fermentation conditions for this strain through one-factor-at-a-time strategy considering seven important factors of shake flask fermentation. Subsequently, composition of fermentation medium was optimized using Box-Behnken design (BBD) of response surface methodology (RSM) including three major nitrogen providing ingredients, namely yeast extract, (NH4)2SO4 and peptone. Maximum D-arabitol concentration produced in one-factor-at-a-time experiments was found to be 72.69 g/L under the optimum conditions consisting of 200 g/L initial glucose, 100 ml medium, 5% (equivalent to 8.78 g/L) initial inoculum, temperature 30 °C, pH 5.0, fermentation time 96 h, and agitation rate 200 rpm. In the experiments of BBD, the predicted yield of D-arabitol varied between 67.73 g/L and 76.76 g/L, while the actual concentration of D-arabitol ranged from 68.02 g/L to 76.95 g/L. The optimum composition of medium F (final medium) contained d-glucose (200 g/L), yeast extract (10 g/L), (NH4)2SO4 (2 g/L) and peptone (7.5 g/L), which further increased D-arabitol production from 72.69 g/L to 76.32 g/L.