Aeromonas australiensis sp. nov., isolated from irrigation water

Abstract

A Gram-negative, facultatively anaerobic bacillus, designated strain 266T, was isolated from an irrigation water system in the south-west of Western Australia. Analysis of the 16S rRNA gene sequence confirmed that strain 266T belonged to the genus Aeromonas , with the nearest species being Aeromonas fluvialis (99.6 % similarity to the type strain, with 6 nucleotide differences) followed by Aeromonas veronii and Aeromonas allosaccharophila (both 99.5 %). Analysis of gyrB and rpoD sequences suggested that strain 266T formed a phylogenetic line independent of other species in the genus. This was confirmed using the concatenated sequences of six housekeeping genes (gyrB, rpoD, recA, dnaJ, gyrA and dnaX) that also indicated that A. veronii and A. allosaccharophila were the nearest relatives. DNA–DNA reassociation experiments and phenotypic analysis further supported the conclusion that strain 266T represents a novel species, for which the name Aeromonas australiensis sp. nov. is proposed, with type strain 266T ( = CECT 8023T  = LMG 2670T).