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Swedish University of Agricultural Sciences

Veterinary bacteriology: information about important bacteria
Veterinary bacteriology


Species/Subspecies: Paenibacillus larvae
Categories: Causes hemolysis; spore forming; motile
Etymology: Genus name: Almost a Bacillus sp.
Species epithet: from larvae.
Significance:American foulbrood is common in the United States, but also occurs in Sweden, Finland and other European countries. The disease can cause significant economic losses where it is prevalent.
  [Important]   
Alternative Species Name(s):Paenibacillus larvae subsp. larvae och P. larvae subsp. pulvifaciens har nu sammanförts till en art.
Taxonomy:
Phylum
Bacillota
Class
Bacilli
Order
Bacillales
Family
Paenibacillaceae 
Genus
Paenibacillus
Type Strain: ATCC 9545 = CCUG 28515.
Macromorphology (smell): Produces mostly greyish-white colonies with diffuse edges. However, there are strains, which form orange pigmented colonies. Some of these (genotype ERIC 3) gives a clear hemolysis zone on blood agar.
Micromorphology:
Paenibacillus larvae  
Spore forming and motile rods (0.5-0.8 x 2.5-5.0 µm), which have peritrichous flagella.
Gram +/Gram -:G+, but difficult to gram stain.
Metabolism: Facultatively anaerobic
Catalase/Oxidase:(-)/?
Other Enzymes: Esculinase +, tryptophanase +, urease -
Biochemical Tests: Citrate -, has mixed acid fermentation (Voges-Proskauer +)
Fermentation of carbohydrates:
D-glucose
+
lactose
?
maltose
?
L-rhamnose
?
sucrose
?
L-arabinose
-
cellobiose
+
D-mannitol
-
salicin
+
trehalose
?
glycerol
+
inulin
?
raffinose
+
D-sorbitol
-
starch
?
Other carbohydrates: Adonitol -, galactose +.
Spec. Char.:
Special Media:
Disease:American foulbrood of honeybees.
Hosts: Honeybee (Apis mellifera)
Clinical Picture: Abnormally high number of dead larvae (even in closed cells). Dead larvae produce a brown viscous residue in the cell, which can be pulled out with a match to a long thread. These residues contain large amounts of bacterial spores and can have a foal smell.
Genome Sequence:
Acc-noStrainSize (bp)Genome
CP003355 04-310 (= DSM 25430) 4 046 337 1c + 1c 
At least three strains have been sequenced and these strains have 0 to 1 circular plasmids.

16S rRNA Seq.:
Acc-noStrainNumber of NTOperon
X60619 ATCC 9545T 1425 

Taxonomy/phylogeny:
Paenibacillus larvae  
About 75 species and subspecies have been described within the genus Paenibacillus. Many of them were earlier regarded as members of the genus Bacillus.
Legislation: On suspicion of American foulbrood (AFB) in Sweden, a complaint is required to the bee inspector or the provincial government by Swedish law. AFB is included in OIE's A-list of major animal diseases.
Comment:Compare Melisococcus plutonius, which causes European foulbrood.
Reference(s): No. 97, 128, 137
Link: Amerikansk yngelröta - biologi, diagnos och bekämpning
Updated:2023-03-08

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