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Strains 2SM5 T and 2SM6, two strictly aerobic chemo-organotrophic gammaproteobacteria, were isolated from Mediterranean seawater off the coast of Vinaroz, Castelló n, Spain, in February, 1990. They were extensively characterized by a polyphasic study that placed them in the genus Pseudomonas. Phylogenetic analysis of 16S rRNA gene sequences showed that both strains shared 100 % sequence similarity and were closely related to members of the Pseudomonas pertucinogena clade, with less than 97.3 % similarity to strains of established species; Pseudomonas xiamenensis was the closest relative. Analysis of sequences of three housekeeping genes, rpoB, rpoD and gyrB, further confirmed the phylogenetic assignment of the Mediterranean isolates. Chemotaxonomic traits such as quinone and polar lipid composition also corroborated the placement of strains 2SM5 T and 2SM6 in the gammaproteobacteria. Other phenotypic traits, including fatty acid composition, enabled clear differentiation of both isolates from other species of Pseudomonas. We therefore conclude that strains 2SM5 T and 2SM6 represent a novel species of Pseudomonas, for which the name Pseudomonas litoralis is proposed; the type strain is 2SM5 T (5CECT 7670 T 5KCTC 23093 T ).The genus Pseudomonas Migula 1894 was described originally to include Gram-negative, strictly aerobic rods that are motile by polar flagella. Pseudomonas includes a large number of species isolated from a variety of natural sources including soil, plants, water and clinical specimens, and has become a very heterogeneous taxon that is characterized by a high level of metabolic diversity (Rosselló et al., 1991;Palleroni, 2005).With the application of modern taxonomic techniques, including rRNA-DNA hybridization studies (Palleroni, 1984) and phylogenetic studies based on 16S rRNA gene sequence comparisons (Moore et al., 1996;Anzai et al., 2000), the genus Pseudomonas has been split into several genera, some even belonging to different subclasses in the phylum 'Proteobacteria', to accommodate bacteria originally described as species of Pseudomonas. In spite of this, the genus Pseudomonas sensu stricto comprises 120 species with names that have been validly published (http://www. bacterio.cict.fr; Yarza et al., 2010). Based on partial sequences of four housekeeping genes (16S rRNA, gyrB, rpoB and rpoD), Mulet et al. (2010) have recently identified two main intrageneric groups (IG) among species of the genus Pseudomonas, called IG Pseudomonas aeruginosa and IG Pseudomonas fluorescens. In their study, some species were placed on phylogenetic branches apart from both lineages, namely Pseudomonas oryzihabitans, Pseudomonas psychrotolerans, Pseudomonas luteola, Pseudomonas pertucinogena and Pseudomonas pachastrellae; among them, the last two always formed the deepest branch. Although not considered in the study by Mulet et al. (2010), other recently described species closely related to P. pertucinogena (Kawai & Yabuuchi, 1975) and P. pachastrellae (Romanenko et al., 2005) (Palleroni, 2005), three of thes...

A facultatively anaerobic marine gammaproteobacterium, designated strain M46 T , was isolated from Mediterranean seawater at Malvarrosa beach, Valencia, Spain. The strain was characterized by using a polyphasic approach and was found to be situated within the genus Photobacterium in the family Vibrionaceae. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain M46 T was closely related to P. rosenbergii CECT 7644 T , P. halotolerans CECT 5860 T and P. ganghwense CECT 7641 T , showing sequence similarities of 96.8, 96.4 and 96.2 %, respectively. According to the results of phylogenetic analyses based on recA and gyrB gene sequences, the most closely related taxon was P. ganghwense CECT 7641 T with 87.4 and 85.0 % sequence similarity, respectively. Regardless of the gene used in phylogenetic analysis, strain M46 T always formed a separate and stable clade containing these three species of the genus Photobacterium. Strain M46 T was not luminescent and produced a diffusible brown pigment. It required NaCl to grow, reduced nitrate to nitrite and oxidized a small number of substrates in Biolog GN plates. Strain M46 T was positive for arginine dihydrolase (ADH), b-galactosidase, aesculin hydrolysis and DNase activity. In API ZYM tests, the novel strain was positive for alkaline phosphatase, leucine arylamidase and acidic phosphatase activities. The major cellular fatty acids were unsaturated C 18 and C 16 , as in other members of the genus Photobacterium, but their relative amounts and the presence or absence of other fatty acids differentiated strain M46 T from its closest relatives. Based on the results of this polyphasic taxonomic study, strain M46 T represents a novel species of the genus Photobacterium, for which the name Photobacterium aphoticum is proposed. The type strain is M46 T (5CECT 7614 T 5KCTC 23057 T ).At the time of writing, the genus Photobacterium, of the family Vibrionaceae, contained sixteen species, most of which were isolated from seawater sampled at different depths, others having been isolated from marine animals. Defined as being facultatively anaerobic and weakly halophilic, species of the genus Photobacterium were originally thought to be mostly luminescent but more than half of the recognized species in the genus do not display this ecologically important character. Only P. phosphoreum, the type species of the genus, P. leiognathi, P. aquimaris, P. kishitanii and P. ganghwense have been described as being luminescent. Some of the luminescent species are symbionts of deep-sea fishes that hold them in specialized luminous organs , while other species, such as P. damselae, are pathogenic for marine animals. Phylogenetic positions of other members of the family Vibrionaceae showed members of the genus Photobacterium grouping with members of the genus Aliivibrio, whose earliest named species, A. fischerii and A. logei were once classified as species of the genus Photobacterium. Members of the recently described genera Grimontia and Enterovibrio also group with P. damselae in ...