Aeromonas bivalvium sp. nov., isolated from bivalve molluscs

Abstract

A polyphasic study was performed to determine the taxonomic position of two Aeromonas strains, 665N and 868E T , isolated from bivalve molluscs, that could not be identified at the species level in a previous numerical taxonomy study. The DNA G+C content of these isolates was 62.3 and 62.6 mol%, respectively. Sequence analysis of the 16S rRNA gene showed that the two new strains were closely related to members of the genus Aeromonas. Fluorescence amplified fragment length polymorphism fingerprinting revealed that strains 665N and 868E T clustered together with a similarity of 78 % but did not cluster with any of the Aeromonas genomospecies. DNA-DNA hybridization experiments revealed a high level of relatedness between the two new isolates (76 %) but low levels of relatedness between these and phylogenetically most closely related Aeromonas genomospecies (30-44 %). Useful tests for the phenotypic differentiation of strains 665N and 868E T from other mesophilic Aeromonas species included those for gas from glucose, lysine decarboxylase, Voges-Proskauer reaction, acid from L-arabinose, hydrolysis of aesculin and utilization of L-lactate. On the basis of genotypic and phenotypic evidence, strains 665N and 868E T are considered to represent a novel species of the genus Aeromonas, for which the name Aeromonas bivalvium sp. nov. is proposed. The type strain is 868E T (=CECT 7113 T =LMG 23376 T ).Members of the genus Aeromonas, belonging to the class Gammaproteobacteria, are Gram-negative, non-spore-forming bacilli or coccobacilli, and are facultatively anaerobic, chemo-organotrophic, oxidase-and catalase-positive, resistant to the vibriostatic agent O/129 (2,4-diamino-6,7-diisopropylpteridine), generally motile by means of a single polar flagellum and are able to reduce nitrate to nitrite. Aeromonads are primarily aquatic, widespread in environmental habitats, frequently isolated from foods and often associated with aquatic animals, and some species are primary or opportunistic pathogens in invertebrates and vertebrates including humans (Martin-Carnahan & Joseph, 2005).At the time of writing, 17 Aeromonas species and 20 DNA-DNA hybridization groups (HGs) have been described: Aeromonas hydrophila (HG1), A. bestiarum (HG2), A. salmonicida (HG3), A. caviae (HG4), A. media (HG5), A. eucrenophila (HG6), A. sobria (HG7), A. veronii bv. Sobria (HG8/10), A. jandaei (HG9), A. veronii bv. Veronii (HG10/ 8), Aeromonas sp. HG11, A. schubertii (HG12), Aeromonas sp. group 501 (HG13), A. trota (HG14), A. allosaccharophila (HG15), A. encheleia (HG16), A. popoffii (HG17), A. culicicola (HG18), A. simiae (HG19) and A. molluscorum (HG20) (Pidiyar et al., 2002; Harf-Monteil et al., 2004; Miñana-Galbis et al., 2004;Martin-Carnahan & Joseph, 2005). In addition to the continuous description of novel species, the complexity of Aeromonas taxonomy results from the isolation of motile and non-motile, mesophilic and psychrophilic, pigmented and non-pigmented strains within several Aeromonas species (Altwegg et al., 1990;Martin-Carnahan & Joseph,...

The GenusAeromonas: Taxonomy, Pathogenicity, and Infection

“…Two phenoms (VI and VII) were identified in this study whose strains could not be assigned to any previously recognized Aeromonas species. Subsequent investigations identified both groups as new species, with phenom VI being proposed as A. molluscorum (205) and phenom VII being proposed as A. bivalvium (206).…”

“…Data from published studies were selected on the basis of study populations, methods of analysis and identification, and other selected factors (7,22,59,129,130,181,195,197,201,205,206,207,223,254 Aeromonas and drinking water. Aeromonas species can be found in various concentrations in drinking water.…”

Use of Cellulolytic Marine Bacteria for Enzymatic Pretreatment in Microalgal Biogas Production

“…These species are associated with human diseases such as gastroenteritis and respiratory infections, are commonly found in aquatic environments (mainly in the guts of mollusks and fish), and have the ability to produce virulence factors (29). To date, there is little information on Aeromonas bivalvium, because it has only recently been described (30). Strains MC18 and MC21 showed 99% and 96% 16S rRNA gene sequence identity, respectively, with Chryseobacterium spp., which, like the species mentioned above, have been described in aquatic environments.…”

Caracterização de Aeromonas spp isoladas de amostras de ostras e água por método microbiológico e molecular

“…Utilizando a técnica de RFLP para identificação das espécies de Aeromonas, provenientes de várias fontes, Alperi et al 27 verificaram que 8,1% das amostras apresentaram padrões de bandas diferentes, levando à identificação duvidosa destas amostras. Para esses autores a microheterogeneidade dos nucleotídeos destas espécies deve ser levada em consideração, quando se usam a RFLP ou outras técnicas moleculares.…”