Related Experiment Video
Updated: Jun 1, 2026
06:12
Quasi-metagenomic Analysis of Salmonella from Food and Environmental Samples
Published on: October 25, 2018
The Salmonella enterica pan-genome
Annika Jacobsen1, Rene S Hendriksen, Frank M Aaresturp
1Department of Systems Biology, Center for Biological Sequence Analysis, Technical University of Denmark, Building 208, 2800 Kongens Lyngby, Denmark.
Microbial Ecology
|June 7, 2011
Summary
Salmonella enterica genomes reveal a stable core genome and abundant accessory genes. Gene content variation, often localized in genomic islands, influences host specificity and pathogenicity.
Area of Science:
- Microbiology
- Genomics
- Bacterial Pathogenesis
Background:
- Salmonella enterica comprises diverse serovars, including significant zoonotic pathogens with varying host specificity.
- Comparative genomics offers insights into bacterial evolution and pathogenicity.
Purpose of the Study:
- To analyze the genomic content of Salmonella enterica using publicly available genome sequences.
- To identify core and accessory genes and understand their distribution and correlation with serotype and host specificity.
Main Methods:
- Comparative analysis of 35 high-quality Salmonella enterica genome sequences and two Escherichia coli strains.
- Standardized gene finding to estimate core and pan-genome size.
- Dendrogram construction to correlate gene content with serotype.
- Visualization of genomic conservation and variation in relation to chromosomal features.
Main Results:
- The core genome of Salmonella was estimated at ~2,800 gene families, with a pan-genome of ~10,000 gene families.
- Gene content showed a non-uniform correlation with serotype.
- Accessory genes, including Salmonella pathogenicity islands (SPIs), phages, and plasmids, contribute significantly to genomic variation.
- Genomic variation is concentrated in specific islands, including SPIs and phage insertion sites.
Conclusions:
- Salmonella genomes possess a stable core but harbor extensive accessory genetic elements.
- Localized genomic variations, particularly in pathogenicity islands and mobile elements, are key drivers of differences among Salmonella strains.
- These variations likely play a crucial role in Salmonella's host specificity and pathogenic potential.
Related Concept Videos
01:08Evolution of Microbial Genome
Microbial genome evolution is a highly dynamic process shaped by continual gene gain and loss across species and strains. This genomic flexibility allows microorganisms to adapt rapidly to environmental pressures and interactions with other organisms. Central to understanding this diversity is the distinction between the core and pan genomes.The core genome comprises the genes shared by all sampled strains of a species, representing essential functions needed for fundamental cellular processes.
01:18Bacterial Gastroenteritis
Bacterial gastroenteritis, characterized by diarrhea, abdominal cramps, and vomiting, is often caused by ingestion of contaminated food or water and is frequently associated with pathogenic Escherichia coli strains. These microbes exploit two principal mechanisms to inflict disease.Shiga toxin–producing E. coli, also referred to as STEC—notably O157:H7—release Shiga toxins that target ribosomes, blocking protein synthesis. The B subunit of the toxin binds the host glycolipid receptor...