''Photorhabdus luminescens'' (previously called ''Xenorhabdus luminescens'') is a

Gammaproteobacterium ''Gammaproteobacteria'' is a class of bacteria in the phylum ''Pseudomonadota'' (synonym ''Proteobacteria''). It contains about 250 genera, which makes it the most genus-rich taxon of the Prokaryotes. Several medically, ecologically, and scienti ...

of the family

Morganellaceae The Morganellaceae are a family of Gram-negative bacteria that include some important human pathogens formerly classified as Enterobacteriaceae. This family is a member of the order Enterobacterales in the class Gammaproteobacteria of the phylum ...

, and is a lethal

pathogen In biology, a pathogen (, "suffering", "passion" and , "producer of"), in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a Germ theory of d ...

insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...

s. It lives in the gut of an

entomopathogenic nematode Entomopathogenic nematodes (EPN) are a group of nematodes (thread worms), that cause death to insects. The term ''entomopathogenic'' has a Greek origin, with ''entomon'', meaning ''insect'', and ''pathogenic'', which means ''causing disease''. T ...

of the family Heterorhabditidae. When the nematode infects an insect, ''P. luminescens'' is released into the blood stream and rapidly kills the insect

host A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places * Host, Pennsylvania, a village in Berks County * Host Island, in the Wilhelm Archipelago, Antarctica People * ...

(within 48 hours) by producing toxins, such as the high molecular weight insecticidal protein complex Tca. ''P. luminescens'' also produces a proteic toxin through the expression of a single gene called ''makes caterpillars floppy'' (mcf). It also secretes

enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

s which break down the body of the infected insect and bioconvert it into

nutrient A nutrient is a substance used by an organism to survive, grow and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi and protists. Nutrients can be incorporated into cells for metabolic purposes or excret ...

s which can be used by both nematode and bacteria. In this way, both organisms gain enough nutrients to replicate (or

reproduce Reproduction (or procreation or breeding) is the biological process by which new individual organisms – "offspring" – are produced from their "parent" or parents. There are two forms of reproduction: asexual and sexual. In asexual reprod ...

in the case of the nematode) several times. The bacteria enter the nematode progeny as they develop.

3,5-Dihydroxy-4-isopropyl-trans-stilbene Tapinarof, also known as benvitimod and sold under the brand name Vtama among others, is a medication used for the treatment of plaque psoriasis. The medication is applied to the skin. Besides its use in medicine, tapinarof is a naturally occ ...

is produced by ''P. luminescens'' bacterial symbiont of the nematode '' Heterorhabditis megidis''. Experiments with ''

Galleria mellonella ''Galleria mellonella'', the greater wax moth or honeycomb moth, is a moth of the family Pyralidae. ''G. mellonella'' is found throughout the world. It is one of two species of wax moths, with the other being the lesser wax moth. ''G. mellonella' ...

'' infected larvae supports the hypothesis that the compound has antibiotic properties that help minimize

competition Competition is a rivalry where two or more parties strive for a common goal which cannot be shared: where one's gain is the other's loss (an example of which is a zero-sum game). Competition can arise between entities such as organisms, indi ...

from other microorganisms and prevents the putrefaction of the nematode-infected insect cadaver. ''P. luminescens'' is

bioluminescent Bioluminescence is the emission of light during a chemiluminescence reaction by living organisms. Bioluminescence occurs in multifarious organisms ranging from marine vertebrates and invertebrates, as well as in some fungi, microorganisms inc ...

; however, the reason for this is not yet properly understood. It has been reported that infection by this bacterium of the wounds of

soldiers A soldier is a person who is a member of an army. A soldier can be a conscripted or volunteer enlisted person, a non-commissioned officer, a warrant officer, or an officer. Etymology The word ''soldier'' derives from the Middle English word ...

in the

American Civil War The American Civil War (April 12, 1861May 26, 1865; also known by Names of the American Civil War, other names) was a civil war in the United States between the Union (American Civil War), Union ("the North") and the Confederate States of A ...

at the

Battle of Shiloh The Battle of Shiloh, also known as the Battle of Pittsburg Landing, was a major battle in the American Civil War fought on April 6–7, 1862. The fighting took place in southwestern Tennessee, which was part of the war's Western Theater of the ...

caused the

wound A wound is any disruption of or damage to living tissue, such as skin, mucous membranes, or organs. Wounds can either be the sudden result of direct trauma (mechanical, thermal, chemical), or can develop slowly over time due to underlying diseas ...

s to glow, and that this aided the survival of the soldiers due to the production of antibiotics by ''P. luminescens''. This led to the phenomenon's nickname "Angel's Glow." There are no contemporary accounts of this phenomenon, meaning that it may be a myth or that conditions including low temperatures, low lighting, abundance of blood, time on battlefield, presence of specific vegetation, presence of rain and humidity, and the time to organize medical evacuation would prevent the phenomenon from recurring in current conditions. ''P. luminescens'' genome has been sequenced. It contains a MACPF protein, however, this molecule appears non-lytic. It also contains the gcvB RNA gene which encodes a small non-coding RNA involved in the regulation of a number of amino acid transport systems as well as amino acid biosynthetic genes. A deletion of the ''hfq'' gene causes loss of secondary metabolite production. It is a source for

bioluminescence imaging Bioluminescence imaging (BLI) is a technology developed over the past decades (1990's and onward). that allows for the noninvasive study of ongoing biological processes Recently, bioluminescence tomography (BLT) has become possible and several ...

References

External links

NCBI genome project
''Photorhabdus luminescens'' subsp. ''laumondii'' TTO1 project at Institut Pasteur
MicrobeWiki
- ''Photorhabdus luminescens'' at Kenyon College's Microbe Wiki
Type strain of ''Photorhabdus luminescens'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
{{Taxonbar, from=Q388648 Enterobacterales Bacteria described in 1979 Taxa named by George Poinar Jr.

See also

References

External links