Vibrio fischeri is a bioluminescent, Gram-negative marine bacterium that can be found free living and in a mutualistic association with certain squids and fishes. Over the past decades, the study of V. fischeri has led to important discoveries about bioluminescence, quorum sensing, and the mechanisms that underlie beneficial host-microbe interactions. This chapter highlights what has been learn...

The marine bacterium Vibrio fischeri serves as a model organism for a variety of natural phenomena, including symbiotic host colonization. The ease with which the V. fischeri genome can be manipulated contributes greatly to our ability to identify the factors involved in these phenomena. Here, we have adapted genetic tools for use in V. fischeri to promote our ability to conditionally control t...

The Vibrio fischeri quorum-sensing signal N-3-oxohexanoyl-l-homoserine lactone (3OC6-HSL) activates expression of the seven-gene luminescence operon. We used microarrays to unveil 18 additional 3OC6-HSL-controlled genes, 3 of which had been identified by other means previously. We show most of these genes are regulated by the 3OC6-HSL-responsive transcriptional regulator LuxR directly. This dem...

Vibrio fischeri is a bioluminescent bacterium that enters into a symbiosis with the bobtail squid Euprymna scolopes. The bacterium colonizes a specialized light organ, in which it generates light that might help the squid to hide its silhouette from animals beneath it. Previous studies have shown that the host nitric oxide (NO) synthase is active during colonization, suggesting that V. fischeri...

We have developed a transposon mutagenesis system for Vibrio fischeri ES114 that utilizes a hyperactive mutant Tn5 transposase (E54K and M56A) and optimized transposon ends. Using a conjugation-based procedure, we obtained independent single-insertion mini-Tn5 mutants at a rate of approximately 10(-6). This simple and inexpensive technique represents a significant improvement over previous meth...

In many bacteria, the twin arginine translocation (Tat) system transports folded proteins across the cytoplasmic membrane, and these proteins can play a role in symbiotic or pathogenic infections. A role for the Vibrio fischeri Tat system was identified during symbiotic colonization of its host Euprymna scolopes, demonstrating a function for the Tat system in host colonization by a member of th...

Vibrio fischeri is the exclusive symbiont residing in the light organ of the squid Euprymna scolopes. To understand the genetic requirements for this association, we searched a library of V. fischeri transposon insertion mutants for those that failed to colonize E. scolopes. We identified four mutants that exhibited severe defects in initiating colonization. Sequence analysis revealed that the ...

Bacterial pathogens typically upregulate the host's production of nitric oxide synthase (NOS) and nitric oxide (NO) as antimicrobial agents, a response that is often mediated by microbe-associated molecular patterns (MAMPs) of the pathogen. In contrast, previous studies of the beneficial Euprymna scolopes/Vibrio fischeri symbiosis demonstrated that symbiont colonization results in attenuation o...

Squids from the genus Euprymna (Cephalopoda: Sepiolidae) and their symbiotic bacteria Vibrio fischeri form a mutualism in which vibrios inhabit a complex light organ within the squid host. A host-mediated daily expulsion event seeds surrounding seawater with symbiotically capable V. fischeri that environmentally colonize newly hatched axenic Euprymna juveniles. Competition experiments using nat...

  This study was carried out to investigate the occurrence of potentially pathogenic species of vibrio in sea water and estuarine environments of the Caspian Sea in the Golestan province of Iran. A total of 127 water samples from coastal waters as well as from river and estuaries were collected and analyzed by culture, during April and September 2001. Following prompt centrifugation, the resusp...