Selection for novel metabolic capabilities in Salmonella enterica

Area of Science:

• Microbiology
• Evolutionary Biology
• Metabolic Engineering

Background:

• Bacteria possess diverse metabolic pathways for utilizing various carbon and energy sources.
• The extent to which bacteria can evolve novel metabolic functions through mutations is not fully understood.

Purpose of the Study:

• To investigate the capacity of bacteria to evolve new metabolic phenotypes.
• To identify the genetic basis for the utilization of novel carbon sources by Salmonella enterica.

Main Methods:

• Large populations of mutagenized Salmonella enterica were cultured on minimal media with 124 novel low molecular weight compounds as sole carbon sources.
• Mutants exhibiting growth on new carbon sources were selected.
• Whole genome sequencing and genetic analysis were performed to identify causal mutations.

Main Results:

• Mutants capable of growing on 18 out of 124 novel carbon sources were obtained.
• Causal mutations were identified for four novel growth phenotypes, including those relieving physiological constraints or enhancing existing pathways.
• The remaining 14 novel phenotypes resulted from combinations of multiple mutations.

Conclusions:

• Bacterial metabolic evolution can lead to the acquisition of novel substrate utilization capabilities.
• Both single and multiple mutations play roles in the evolution of new metabolic pathways and phenotypes.
• This study provides insights into the adaptive landscape governing the evolution of novel metabolic functions in bacteria.