Enterochelin (enterobactin): virulence factor for Salmonella typhimurium

Area of Science:

• Microbiology
• Bacterial Pathogenesis
• Molecular Biology

Background:

• Salmonella typhimurium's ability to synthesize enterochelin (ENT) influences its growth and virulence.
• Enterochelin is essential for bacterial iron uptake and survival in host environments.

Purpose of the Study:

• To investigate the role of enterochelin (ENT) as a virulence factor in Salmonella typhimurium.
• To characterize an ENT-deficient mutant and assess its growth and pathogenicity compared to the wild-type strain.

Main Methods:

• Derivation of an ENT-deficient mutant (96-1) from a virulent Salmonella typhimurium strain (SR-11).
• Assessment of bacterial growth in complement-inactivated human serum with and without ENT supplementation.
• Evaluation of bacterial growth and survival in vivo using mouse models (peritoneal injection) and determination of the 50% lethal dose (LD50).

Main Results:

• The ENT mutant (96-1) showed significantly inhibited growth in serum, which was restored by ENT addition.
• In vivo, the ENT mutant exhibited markedly inhibited growth without ENT, but enhanced growth with ENT supplementation, surpassing the wild-type strain.
• The ENT mutant had a 2-3 log unit higher LD50 than the wild-type strain, which was dose-dependently reduced by ENT administration.

Conclusions:

• Enterochelin (ENT) is a critical virulence factor for Salmonella typhimurium.
• ENT facilitates bacterial growth and survival in host environments, contributing to pathogenicity.
• Supplementation with ENT can restore the virulence of ENT-deficient mutants to wild-type levels.