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Swedish University of Agricultural Sciences

Veterinary bacteriology: information about important bacteria
Veterinary bacteriology


Species/Subspecies: Actinobacillus equuli subsp. equuli
Etymology: Genus name: small ray rod.
Species epithet: from a foal.
Subspecies epithet: see subspecies epithet.
Significance:  [Very important]   
Alternative Species Name(s):Actinobacillus equuli
Taxonomy:
Phylum
Pseudomonadota
Class
Gammaproteobacteria
Order
Pasteurellales
Family
Pasteurellaceae 
Genus
Actinobacillus
Type Strain: ATCC 19392 = CCUG 2041 = NCTC 8529
Macromorphology (smell):
   
Forms very viscous colonies with no hemolysis on blood agar.
Micromorphology: Rod shaped (0.3-0.5 x 0.6-1.4 µm) and non-motile. Long (up to 6 µm) filamentous forms are formed if the medium contains glucose or maltose.
Gram +/Gram -:
 
G-
Metabolism: Facultatively anaerobic
Catalase/Oxidase:V/+
Other Enzymes: Ornithine decarboxylase -, urease +, tryptophanase -.
Biochemical Tests: Methyl red -, Voges-Proskauer -, hydrogen sulfide V
Fermentation of carbohydrates:
D-glucose
+
lactose
+
maltose
+
L-rhamnose
-
sucrose
+
L-arabinose
v
cellobiose
-
D-mannitol
+
salicin
-
trehalose
+
glycerol
v
inulin
-
raffinose
?
D-sorbitol
-
starch
v
Other carbohydrates: Adonitol -, dulcitol -, D-fructose +, D-galactose +, inositol -, D-mannose +, melibiose +.
Spec. Char.: Does not require V-factor (NAD or NADPH) for growth. Cf. other Actinobacillus spp.
Special Media:
Actinobacillus equuli  
A. equuli subsp. equuli can be cultivated on purple agar and ferments lactose under acid production (see Fig. 107:3).
Disease:See table
HostsDiseaseClinical picture
PigsActinobacillosisArhritis in piglets and endocarditis in older pigs
Horses (foal)Sleepy foal diseaseSepticaemia, arthritis, pneumonia och neophritis
Genome Sequence:
Acc-noStrainSize (bp)Genome
Not reported    

16S rRNA Seq.:
Acc-noStrainNumber of NTOperon
M75072 (T) 1477  

Taxonomy/phylogeny:
 
About 18 species have been described within genus Actinobacillus, but the relationship between members within the closely related genera Actinobacillus, Haemophilus, Mannheimia and Pasteurella is very uncertain since none of these genera forms monophyletic clusters.
Reference(s): No. 32
Updated:2023-03-29

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