Aeromonas encheleia sp. nov., Isolated from European Eels

Abstract

Four strains isolated from European eels in Valencia, Spain, were found to constitute a DNA relatedness group which is 0 to 50% related to the 13 species and DNA group 11 of the genus Aeromonas. Phenotypically, these strains have all of the properties that define the genus Aeromonas. However, they differ from the previously described Aeromonas species by three or more properties. The strains are positive for motility, growth at 37"C, indole production, and arginine dihydrolase activity. They exhibit negative reactions in tests for growth at 42°C and in thiosulfate-citrate-bile salts-sucrose medium (Oxoid), Simmons citrate tests, and tests for lysine and ornithine decarboxylase activities. They produce acid from salicin but not from L-arabinose, D-cellobiose, or lactose. All four strains hydrolyze esculin and arbutin but not elastin. They use L-serine as a sole carbon and energy source but cannot utilize L-arabinose, L-arginine, D-gluconate, or L-glutamine. The strains are resistant to ampicillin. The guanine-plus-cytosine content of the DNA is 59.4 to 60.8 mol%. The name Aeromonas encheleia sp. nov. is proposed for these strains; strain S181 (= CECT 4342) is the type strain. This new species is generally not pathogenic for eels or mice.The genus Aeromonas was proposed by Kluyver and van Niel in 1936 (23) and comprises a collection of oxidase-and catalase-positive, glucose-fermenting, facultatively anaerobic, gram-negative, rod-shaped bacteria that are resistant to vibriostatic agent OD29 (2,4-diamino-6,7-diisopropyl pteridine) and generally are motile by means of polar flagella (32). Bergey's Manual of Systematic Bacteriology includes four species in the genus Aeromonas, Aerornonas salmonicida, Aerornonas hydrophila, Aerornonas caviae, and Aerornonas sobria, some of which are genotypically heterogeneous (32, 34). Recently, the number of recognized species in the genus Aerornonas has increased from 4 to 13; these species represent clearly differentiated DNA homology groups (2, 6, 7, 13, 14, 38-40). Furthermore, methods for identification of Aeromonas strains at the genus and species levels have undergone major improvements primarily as a result of chemotaxonomic studies (3, 4, During a survey to determine what bacteria are associated with European eels reared in a freshwater farm located in Valencia, Spain, four phenotypically related strains were isolated. These strains could not be identified as members of any previously described Aerornonas species. The purposes of this study were to determine, by DNA-DNA hybridization and extensive phenotypic tests, the taxonomic position of the four eel isolates and to assess by inoculation in animal models the pathological significance of these organisms. In this paper we describe a new species, Aeromonas encheleia, which is generally not pathogenic for eels or mice. 20). MATERIALS AND METHODSBacterial strains. The four strains of A. encheleiu used in this study (S176, S177, S181T [T = type strain], and S191) were recovered from healthy European eels reared in a freshwater ...

Dominant pathogenic species of mesophilic aeromonads isolated from diseased and healthy fish cultured in Poland

“…However, with improvements in the taxonomy of this group of bacteria, it is a matter of speculation whether or not the pathogenic fish isolates belong to A. hydrophila or to another Aeromonas species (Austin & Austin 1999). Aeromonas hydrophila sensu stricto was reported previously as pathogenic for eel (Esteve et al. 1995a,b) and in this study was found associated with disease in rainbow trout.…”

“…The genus Aeromonas is represented by at least 14 valid species: A. hydrophila ( sensu stricto ), A. bestiarum , A. salmonicida (comprising non‐motile and psychrophilic as well as motile and mesophilic biogroups), A. caviae ( sensu stricto ), A. media , A. eucrenophila , A. sobria ( sensu stricto ), A. veronii (with two biotypes sobria and veronii ), A. jandaei , A. trota , A. schuberti , A. encheleia , A. allosaccharophila and A. popoffi (Janda 1991; Martinez‐Murcia, Esteve, Garay & Collins 1992; Joseph & Carnahan 1994; Esteve, Gutiérrez & Ventosa 1995b; Ali, Carnahan, Altwegg, Lüthy‐Hottenstein & Joseph 1996; Huys, Kämpfer, Altwegg, Coopman, Janssen, Gillis & Kersters 1997a; Huys, Kämpfer, Altwegg, Kersters, Lamb, Coopman, Lüthy‐Hottenstein, Vancanneyt, Janssen & Kersters 1997b). Of these, A. hydrophila , A. bestiarum , A. salmonicida , A. veronii bt.…”

Distinct Aeromonas Populations in Water Column and Associated with Copepods from Estuarine Environment (Seine, France)

“…Indeed, such Aeromonas species could be well adapted to a estuarine environment having a cooler surface water with mean temperature of 13.4°C (min: 5.3°C/ max 21.3°C). Except for A. salmonicida (Henriques et al, 2006), these species, previously observed in farmed fishes (water and fish) (Esteve et al, 1995; Schmidt et al, 2001; Hatha et al, 2005; Behbahani et al, 2014; Bartkova et al, 2016) and in waste water (Figueira et al, 2011; Marti and Balcázar, 2015; Popovic et al, 2015; Vaz-Moreira et al, 2015; Varela et al, 2016), have never been, as far as we know, described in coastal and anthropized estuary waters. Only the species A. hydrophila , A. caviae , A. sobria , and A. veronii have been reported in coastal or estuarine environments (the Adriatic Sea, Italy) (Dumontet et al, 1996; Fiorentini et al, 1998; Gugliandolo et al, 2008).…”

The MainAeromonasPathogenic Factors

“…sobria (HG8) and bv. veronii (HG10)], A. jandaei (HG9), A. schubertii (HG12), A. trota (HG14), A. allosaccharophila (HG15) [6], A. encheleia (HG16) [10], and A. popoffii (HG17) [11]; recently three new species have been described: A. culicicola [12], A. simiae [13], and A. molluscorum [14]. Two DNA-hybridisation groups, Aeromonas sp.…”