Phylogeny of Vibrio cholerae based on recA sequence

Area of Science:

• Microbiology
• Genetics
• Molecular Biology

Background:

• Vibrio cholerae is a significant human pathogen.
• Understanding the genetic diversity and evolutionary relationships within V. cholerae is crucial for public health and diagnostics.
• The recA gene is a useful marker for bacterial phylogeny.

Purpose of the Study:

• To investigate the phylogenetic relationships among Vibrio cholerae strains and closely related species using the recA gene.
• To assess the correlation between traditional V. cholerae serogroup designations and molecular phylogeny.
• To explore the potential mechanisms driving genetic diversity in V. cholerae.

Main Methods:

• Sequencing of a 705-bp fragment of the recA gene from 113 Vibrio cholerae strains and related species.
• Phylogenetic analysis of informative and uninformative nucleotide sites.
• Comparison of recA-based phylogeny with biochemical characteristics and serogroup designations.

Main Results:

• Phylogenetic analysis revealed distinct clustering of Vibrio parahaemolyticus and Vibrio vulnificus as out-groups.
• Some isolates biochemically resembling V. cholerae did not cluster with confirmed V. cholerae strains.
• A significant discordance was observed between V. cholerae serogroup designations and recA gene phylogeny.
• recA sequence divergence indicated a lack of correlation between serogroup and genetic relatedness.

Conclusions:

• Traditional V. cholerae serogroup designations are not always reliable indicators of phylogenetic relationships.
• The observed phylogenetic patterns support the hypothesis of horizontal gene transfer of O-antigen biosynthesis genes within V. cholerae.
• Genetic diversity in V. cholerae is shaped by factors beyond simple vertical inheritance, including horizontal gene transfer.