(585k) Metabolomic Study Of Propionibacterium Acidipropionici ATCC 4875 Revealed The Metabolic Regulations In Response To FBB Adaptation and Different pH Values

Drastic alterations in FBB adaptation are known to cause large changes in metabolism in Propionibacterium acidipropionici. The pH value could affect the propionic acid production in P. acidipropionici fermentation. Metabolomics was used to study the possible metabolic regulations leading to the enhanced propionic acid production in the FBB adapted cells and how pH could have affected the metabolic pathway in propionic acid biosynthesis. As a result of the rapid sampling, extraction, and analysis by gas chromatography coupled to time-of-flight mass spectrometry (GC-TOF/MS), more than 572 analytes from a single sample could be measured, of which 140 metabolites of their chemical structures and names have been identified. Wild-type, FBB adapted and cells at pH 6.5 and pH 5.5 after high cell density fermentation were clustered into four groups after orthogonal projection on latent structure discriminant analysis (OPLS-DA) pattern recognition due to their highly distinctive metabolite profiles. Compared to the wild type, FBB adapted mutant biosynthesized less polysaccharide which contributed to that more C sources were directed toward propionic acid biosynthesis. The N-compounds mainly nucleotides decreased in FBB adapted cells, indicating reduced cell growth activity. Amino acids, whose biosynthesis requires large amounts of ATP and NADPH, also decreased in FBB-adapted cells. The cell membrane composition also changed in the adapted cells with more long-chain saturated fatty acids and less unsaturated fatty acids compared to the wild type. Cells after high cell density fermentation at pH 5.5 showed lower concentrations of pyruvate, succinate and lactate, confirming that more propionic acid was produced from the substrate carbon with less diverted to other byproducts as observed in the fermentation. Overall, metabolic alterations could be assigned to central metabolic pathways such as glycolysis, Wood-Werkman cycle, TCA cycle, nucleotide and amino acids metabolism, which will be discussed in this paper.