Aeromonas bivalvium sp. nov. isolated from bivalve molluscs

Abstract

A polyphasic study was performed to determine the taxonomic position of two <i>Aeromonas</i> 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 <i>Aeromonas</i>. 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 <i>Aeromonas</i> 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 <i>Aeromonas</i> genomospecies (30-44 %). Useful tests for the phenotypic differentiation of strains 665N and 868E^T from other mesophilic <i>Aeromonas</i> 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 868ET are considered to represent a novel species of the genus <i>Aeromonas</i>, for which the name <i>Aeromonas bivalvium</i> sp. nov. is proposed. The type strain is 868E^T (=CECT 7113^T=LMG 23376^T).