Abstract:[Objective]This study aims to increase the caproic acid yield of Aneurinibacillus JXN-1.[Method]First, a Plackett-Burman design was employed to screen the significant factors affecting caproic acid yield from eight medium components. Subsequently, the path of steepest ascent method was used to determine the optimal concentration ranges of these significant factors. Finally, a Box-Behnken design was utilized to establish a quadratic polynomial regression model, and the interactions among the significant factors were analyzed to predict the optimal medium composition.[Result]The Plackett-Burman design identified the mass concentrations of sodium acetate and calcium folinate and the volume fraction of ethanol as significant influencing factors. The regression model established by the Box-Behnken design was highly significant (P<0.01). The predicted optimal medium composition was as follows: sucrose mass concentration of 7.50 g/L, yeast extract mass concentration of 1.00 g/L, magnesium sulfate heptahydrate mass concentration of 0.20 g/L, sodium acetate mass concentration of 4.08 g/L, ammonium sulfate mass concentration of 0.45 g/L, calcium folinate mass concentration of 2.88 mg/L, dipotassium hydrogen phosphate mass concentration of 0.60 g/L, and ethanol volume fraction of 2.53%. Under these conditions, the actual caproic acid yield was in high agreement with the model predicted value, representing an increase of 212.47% compared with the pre-optimization level.[Conclusion]This study successfully optimizes the fermentation medium for caproic acid production by Aneurinibacillus JXN-1. The optimized medium significantly enhances the caproic acid yield, providing a theoretical basis and technical reference for the practical application of this strain in Baijiu brewing.
