Metabolic profiling analysis of the vitamin B ₁₂ producer Propionibacterium freudenreichii

Abstract

Vitamin B ₁₂ (VB ₁₂) 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 VB ₁₂ production by Propionibacterium freudenreichii were evaluated and optimized based on statistical experiments. The results showed that glucose, yeast extract, KH ₂PO ₄, and glycine have significant effects on VB ₁₂ production. The final titer of VB ₁₂ 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 VB ₁₂ 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 VB ₁₂ due to an improved supply of energy and precursors.

Abstract

The metabolomics approach was employed to analyze the differences of metabolite concentrations in Propionibacterium freudenreichii cultivated in different media, explaining the differences in growth, fermentation characteristics, and vitamin B ₁₂ (VB ₁₂) production. Using multivariate data analysis, we illustrated how metabolomics can be used to explain VB ₁₂ production changes by corresponding differences in the overall cellular metabolism. The key metabolic nodes of VB ₁₂ synthesis in P. freudenreichii were identified, which may contribute to the metabolic engineering of this organism to improve industrial VB ₁₂ production.