Independent host- and bacterium-based determinants protect a model symbiosis from phage predation.

Bacteriophages (phages) are diverse and abundant constituents of microbial communities worldwide, capable of modulating bacterial populations in diverse ways. Here, we describe the phage HNL01, which infects the marine bacterium Vibrio fischeri. We use culture-based approaches to demonstrate that mutations in the exopolysaccharide locus of V.

HbtR, a Heterofunctional Homolog of the Virulence Regulator TcpP, Facilitates the Transition between Symbiotic and Planktonic Lifestyles in Vibrio fischeri.

The bioluminescent bacterium forms a mutually beneficial symbiosis with the Hawaiian bobtail squid, , in which the bacteria, housed inside a specialized light organ, produce light used by the squid in its nocturnal activities. Upon hatching, juveniles acquire from the seawater through a complex process that requires, among other factors, chemotaxis by the bacteria along a gradient of -acetylated sugars into the crypts of the light organ, the niche in which the bacteria reside. Once inside the light organ, transitions into a symbiotic, sessile state in which the quorum-signaling regulator LitR induces luminescence.

Ambient pH Alters the Protein Content of Outer Membrane Vesicles, Driving Host Development in a Beneficial Symbiosis.

Outer membrane vesicles (OMVs) are continuously produced by Gram-negative bacteria and are increasingly recognized as ubiquitous mediators of bacterial physiology. In particular, OMVs are powerful effectors in interorganismal interactions, driven largely by their molecular contents. These impacts have been studied extensively in bacterial pathogenesis but have not been well documented within the context of mutualism.

Survival of Anaerobic Fe Stress Requires the ClpXP Protease.

strain MR-1 is a versatile bacterium capable of respiring extracellular, insoluble ferric oxide minerals under anaerobic conditions. The respiration of iron minerals results in the production of soluble ferrous ions, which at high concentrations are toxic to living organisms. It is not fully understood how Fe is toxic to cells anaerobically, nor is it fully understood how is able to resist high levels of Fe Here we describe the results of a transposon mutant screen and subsequent deletion of the genes and in , which demonstrate that the protease ClpXP is required for anaerobic Fe resistance.

A Ferrous Iron Exporter Mediates Iron Resistance in Shewanella oneidensis MR-1.

Shewanella oneidensis strain MR-1 is a dissimilatory metal-reducing bacterium frequently found in aquatic sediments. In the absence of oxygen, S. oneidensis can respire extracellular, insoluble oxidized metals, such as iron (hydr)oxides, making it intimately involved in environmental metal and nutrient cycling.