Metabolic profiling analysis of the vitamin B₁₂ producer Propionibacterium freudenreichii

Vitamin B₁₂ (VB₁₂ ) is an indispensable cofactor of metabolic enzymes and has been widely used in the food and pharmaceutical industries. In this study, the effects of medium composition on VB₁₂ production by Propionibacterium freudenreichii were evaluated and optimized based on statistical experiments. The results showed that glucose, yeast extract, KH₂ PO₄ , and glycine have significant effects on VB₁₂ production. The final titer of VB₁₂ reached 8.32 ± 0.02 mg/L, representing a 120% increase over the non-optimized culture medium. We employed a metabolomics approach to analyze the differences of metabolite concentrations in P. freudenreichii cells cultivated in the original medium and optimized fermentation medium. Using multivariate data analysis, we identified a range of correlated metabolites, illustrating how metabolomics can be used to explain VB₁₂ production changes by corresponding differences in the overall cellular metabolism. The concentrations of many metabolic intermediates of glycolysis, the Wood-Werkman cycle, the TCA cycle, and amino acid metabolism were increased, which contributed to the synthesis of propionic acid and VB₁₂ due to an improved supply of energy and precursors.