Mapping Salmonella typhimurium pathways using ¹³C metabolic flux analysis

Area of Science:

• Microbial metabolism and metabolic engineering
• Systems biology and bioinformatics

Background:

• Salmonella is a significant pathogen and a potential host for producing pharmaceutical compounds.
• Understanding Salmonella metabolism is crucial for its exploitation as a bioproduct delivery platform.
• Genome-scale metabolic models aid in designing metabolic engineering strategies.

Purpose of the Study:

• To map metabolic fluxes in the central carbon pathways of Salmonella Typhimurium LT2.
• To assess the performance of a genome-scale metabolic model using experimental flux data.
• To improve metabolic engineering strategies for Salmonella-based bioproduct delivery.

Main Methods:

• Utilized 13C-MFA (13C-based Metabolic Flux Analysis) in glucose-limited chemostat cultures of S. typhimurium LT2.
• Experiments conducted in a 2L bioreactor with defined medium and 13C-labeled glucose.
• Estimated metabolic flux distributions using OpenFLUX2, analyzing biomass protein hydrolysate labeling patterns and biomass composition.

Main Results:

• Pentose phosphate pathway is predominantly used for glucose catabolism, with minimal flux through glycolysis.
• In silico simulations using Optflux and pFBA improved model accuracy when integrating estimated intracellular fluxes.
• The genome-scale model showed better fitting to experimental extracellular fluxes but poorly described intracellular fluxes in the pentose phosphate and anaplerotic pathways.

Conclusions:

• The pentose phosphate pathway plays a key role in S. typhimurium LT2 central carbon metabolism.
• Integrating experimentally determined intracellular fluxes enhances the predictive accuracy of genome-scale metabolic models.
• Further refinement of metabolic models is needed to accurately represent specific intracellular pathways for improved bioproduct engineering.