The catalase gene, katA, of the sepiolid squid symbiont Vibrio fischeri has been cloned and sequenced. The predicted amino acid sequence of KatA has a high degree of similarity to the recently defined group III catalases, including those found in Haemophilus influenzae, Bacteroides fragilis, and Proteus mirabilis. Upstream of the predicted start codon of katA is a sequence that closely matches ...

Bacteria successfully colonize distinct niches because they can sense and appropriately respond to a variety of environmental signals. Of particular interest is how a bacterium negotiates the multiple, complex environments posed during successful infection of an animal host. One tractable model system to study how a bacterium manages a host's multiple environments is the symbiotic relationship ...

UNLABELLED Most animal-microbe mutualistic associations are characterized by nutrient exchange between the partners. When the host provides the nutrients, it can gain the capacity to shape its microbial community, control the stability of the interaction, and promote its health and fitness. Using the bioluminescent squid-vibrio model, we demonstrate how a single host-derived glycan, chitin, reg...

UNLABELLED Using the squid-vibrio association, we aimed to characterize the mechanism through which Vibrio fischeri cells signal morphogenesis of the symbiotic light-emitting organ. The symbiont releases two cell envelope molecules, peptidoglycan (PG) and lipopolysaccharide (LPS) that, within 12 h of light organ colonization, act in synergy to trigger normal tissue development. Recent work has ...

The bioluminescent bacteria emit light in a broad spectral distribution with a spectral maximum in the range 472—505 nm (1—3). The emission maxima (Ama, = 475—486 nm) from some strains of Photobacterium phosphoreum and P. leiognathi are blue-shifted with respect to the emission spectra (Xm^ = = 495 nm) from the in vitro reaction of their luciferases with FMNH2? aldehyde and oxygen alone (3). Th...

Magnesium-dependent induction of Vibrio fischeri flagellar (Mif) biogenesis depends upon two diguanylate cyclases, suggesting an inhibitory role for cyclic di-GMP. Here, we report that cells defective for the sugar phosphotransferase system (PTS) exhibited a magnesium-independent phenotype similar to that of mutants of the Mif pathway. Unlike Mif mutants, PTS mutants also were hyperbioluminescent.

NfsB is an oxygen-insensitive nitroreductase of Escherichia coli with significant amino acid sequence homology to the major flavin reductase (FRase I) of Vibrio fischeri. Here, we show that NfsB is convertible to an FRase I-like flavin reductase three times as active as the authentic FRase I by a single amino acid substitution in the least-conserved region.

Vibrio fischeri ES114 is a bioluminescent symbiont of the squid Euprymna scolopes. Like most isolates from E. scolopes, ES114 produces only dim luminescence outside the host, even in dense cultures. We previously identified mutants with brighter luminescence, and here we report their symbiotic phenotypes, providing insights into the host environment.

We demonstrate an approach to the surface-mediated release of a synthetic N-acylated L-homoserine lactone (AHL) modulator of bacterial quorum sensing (QS). AHL released gradually from thin films of poly(lactide-co-glycolide) (PLG) is shown to activate QS in the model symbiont Vibrio fischeri at levels that exceed those promoted by direct solution-based administration.

Vibrio vulnificus was found to produce a chemical that induced the expression of Vibrio fischeri lux genes. Electron spray ionization-mass spectrometry and 1H nuclear magnetic resonance analyses indicated that the compound was cyclo(L-Phe-L-Pro) (cFP). The compound was produced at a maximal level when cell cultures reached the onset of stationary phase. Sodium dodecyl sulfate-polyacrylamide gel...