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Updated: Jun 12, 2026

Methodology for the Study of Horizontal Gene Transfer in Staphylococcus aureus
10:39

Methodology for the Study of Horizontal Gene Transfer in Staphylococcus aureus

Published on: March 10, 2017

Identification of horizontal gene transfer and recombination of PsaA gene in streptococcus mitis group

Qiao Zhang1, Qianli Ma, Dan Su

  • 1Institute of Respiratory Diseases, Xinqiao Hospital, Third Military Medical University, No. 183 Xinqiao Street, Chongqing 400037, China.

Microbiology and Immunology
|June 12, 2010
PubMed

Insights

The pneumococcal surface adhesin A (psaA) gene is not specific to Streptococcus pneumoniae. High-frequency horizontal gene transfer explains its presence in other species within the Streptococcus mitis group.

Area of Science:

  • Microbiology
  • Genetics
  • Evolutionary Biology

Background:

  • The pneumococcal surface adhesin A (psaA) gene is a known adhesion gene in Streptococcus pneumoniae.
  • Its species-specificity for Streptococcus pneumoniae remains a subject of debate.

Purpose of the Study:

  • To investigate the presence and evolutionary history of the psaA gene in the Streptococcus mitis group.
  • To determine if psaA is a species-specific gene for Streptococcus pneumoniae.

Main Methods:

  • Polymerase Chain Reaction (PCR) was used to detect the psaA gene in 34 Streptococcus mitis group isolates.
  • Sequencing of PCR products and phylogenetic analysis using housekeeping genes (sodA, rnpB) and psaA were performed.

Main Results:

  • The psaA gene showed high sequence conservation (92.6-100%) across Streptococcus pneumoniae and other Streptococcus mitis group species.
  • Phylogenetic analysis indicated vertical inheritance of psaA only in Streptococcus pneumoniae.
  • High-frequency horizontal gene transfer (HGT) and recombination of the psaA gene were observed in other Streptococcus mitis group species.

Conclusions:

  • The psaA gene is not exclusive to Streptococcus pneumoniae.
  • Frequent HGT and recombination events likely account for the presence of psaA in other Streptococcus mitis group species.

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