Aliivibrio logei KCh1 (Kamchatka isolate): Biochemical and bioluminescence characteristics and cloning of the lux operon

Abstract Although bioluminescent bacteria are the most abundant and widely distributed of all light-emitting organisms, the biological role and evolutionary history of bacterial luminescence are still shrouded in mystery. Bioluminescence has so far been observed in the genomes of three families of Gammaproteobacteria in the form of canonical lux operons that adopt the CDAB(F)E(G) gene order. LuxA and luxB encode the two subunits of bacterial luciferase responsible for light-emission. Our deep exploration of public marine environmental databases considerably expands this view by providing a catalog of new lux homolog sequences, including 401 previously unknown luciferase-related genes. It also reveals a broader diversity of the lux operon organization, which we observed in previously undescribed configurations such as CEDA, CAED and AxxCE. This expanded operon diversity provides clues for deciphering lux operon evolution and propagation within the bacterial domain. Leveraging quantitative tracking of marine bacterial genes afforded by planetary scale metagenomic sampling, our study also reveals that the novel lux genes and operons described herein are more abundant in the global ocean than the canonical CDAB(F)E(G) operon.

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Colonization of Host Plants by the Fire Blight Pathogen Erwinia amylovora Marked with Genes for Bioluminescence and Fluorescence

Phytopathology ◽

10.1094/phyto.1998.88.5.416 ◽

1998 ◽

Vol 88 (5) ◽

pp. 416-421 ◽

Cited By ~ 58

Author(s):

Jochen Bogs ◽

Iris Bruchmüller ◽

Claudia Erbar ◽

Klaus Geider

Keyword(s):

Host Plants ◽

Fire Blight ◽

Erwinia Amylovora ◽

Vibrio Fischeri ◽

Bacterial Invasion ◽

Leaf Hairs ◽

Lux Operon ◽

And Migration ◽

Green Fluorescent ◽

Lac Promoter

To follow the movement of Erwinia amylovora in plant tissue without dissection, this bacterium was marked with either the lux operon from Vibrio fischeri or the gfp gene from the jellyfish Aequorea victoria, both carried on multicopy plasmids and expressed under the control of the lac promoter from Escherichia coli. Movement of the pathogen was visualized in leaves, stems, and roots of apple seedlings, and migration of E. amylovora was traced from inoculation sites in the stem to as far as the roots. Green fluorescent E. amylovora cells were observed in the xylem and later appeared to break out of the vessels into the intercellular spaces of the adjacent parenchyma. Inoculation in the intercostal region of leaves caused a zone of slow necrosis that finally resulted in bacterial invasion of the xylem vessels. Labeled bacteria could also be seen in association with the anchor sites of leaf hairs. Distortion of the epidermis adjacent to leaf hairs created openings that were observed by scanning electron microscopy. As the intercostal region, the bases of leaf hairs provided E. amylovora access to intact xylem vessels, which allowed further distribution of the pathogen in the host plant.

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