Catabolic pathway acquisition by rhizosphere bacteria readily enables growth with a root exudate component but does not affect root colonization.

Horizontal gene transfer (HGT) is a fundamental evolutionary process that plays a key role in bacterial evolution. The likelihood of a successful transfer event is expected to depend on the precise balance of costs and benefits resulting from pathway acquisition. Most experimental analyses of HGT have focused on phenotypes that have large fitness benefits under appropriate selective conditions, such as antibiotic resistance.

Relative Contributions of and Bacteriophage to Bacterial Cell Death under Various Environmental Conditions.

The role of protists and bacteriophages in bacterial predation in the microbial food web has been well studied. There is mounting evidence that and like organisms (BALOs) also contribute to bacterial mortality and, in some cases, more so than bacteriophages. A full understanding of the ecologic function of the microbial food web requires recognition of all major predators and the magnitude of each predator's contribution.

Titration of Folate Pathway Enzymes.

How enzymes behave in cells is likely different from how they behave in the test tube. Previous studies find that osmolytes interact weakly with folate. Removal of the osmolyte from the solvation shell of folate is more difficult than removal of water, which weakens binding of folate to its enzyme partners.

Halobacteriovorax, an underestimated predator on bacteria: potential impact relative to viruses on bacterial mortality.

Predation on bacteria and accompanying mortality are important mechanisms in controlling bacterial populations and recycling of nutrients through the microbial loop. The agents most investigated and seen as responsible for bacterial mortality are viruses and protists. However, a body of evidence suggests that predatory bacteria such as the Halobacteriovorax (formerly Bacteriovorax), a Bdellovibrio-like organism, contribute substantially to bacterial death.

Niche partition of Bacteriovorax operational taxonomic units along salinity and temporal gradients in the Chesapeake Bay reveals distinct estuarine strains.

The predatory Bacteriovorax are Gram-negative bacteria ubiquitous in saltwater systems that prey upon other Gram-negative bacteria in a similar manner to the related genus Bdellovibrio. Among the phylogenetically defined clusters of Bacteriovorax, cluster V has only been isolated from estuaries suggesting that it may be a distinct estuarine phylotype. To assess this hypothesis, the spatial and temporal distribution of cluster V and other Bacteriovorax phylogenetic assemblages along the salinity gradient of Chesapeake Bay were determined.

Predatory Bacteriovorax communities ordered by various prey species.

The role of predation in altering microbial communities has been studied for decades but few examples are known for bacterial predators. Bacteriovorax are halophilic prokaryotes that prey on susceptible gram-negative bacteria. We recently reported novel observations on the differential selection of Bacteriovorax phylotypes by two different prey, Vibrio parahaemolyticus and Vibrio vulnificus.