From the Inside Out: an Epibiotic Bdellovibrio Predator with an Expanded Genomic Complement

Area of Science:

• Microbiology
• Bacteriology
• Evolutionary Biology

Background:

• Bdellovibrio and like organisms are abundant bacterial predators with diverse predation strategies.
• Most known Bdellovibrio species replicate within the prey's periplasm (intraperiplasmic).
• Few Bdellovibrio species exhibit epibiotic predation, consuming prey externally.

Purpose of the Study:

• To characterize a novel epibiotic Bdellovibrio species, "Candidatus Bdellovibrio qaytius" (Ca. B. qaytius).
• To investigate the genomic and phylogenetic characteristics of Ca. B. qaytius.
• To determine the evolutionary implications of Ca. B. qaytius's predation strategy and genomic makeup.

Main Methods:

• Isolation and cultivation of "Candidatus Bdellovibrio qaytius" from a freshwater pond.
• Genomic sequencing and functional annotation of Ca. B. qaytius.
• Phylogenetic analysis of Ca. B. qaytius within the Bdellovibrio genus.

Main Results:

• "Ca. B. qaytius" was isolated and found to prey on "Paraburkholderia fungorum" epibiotically.
• Despite its external predation, Ca. B. qaytius possesses a large genome with biosynthesis pathways typically found in intraperiplasmic predators.
• Phylogenetic analysis places Ca. B. qaytius in a basal cluster, suggesting epibiotic predation might be an ancestral trait.

Conclusions:

• "Ca. B. qaytius" represents an intermediate phenotype between epibiotic and intraperiplasmic predators.
• The genomic data narrows down the specific genetic components of epibiotic predators.
• Epibiotic predation is likely a common and potentially ancestral predation strategy within the Bdellovibrio genus.