Four strains of marine, aerobic, agar-decomposing bacteria with one polar flagellum and with DNA G+C contents of 3809402 mol% were isolated from the Far-Eastern mussels Crenomytilus grayanus and Patinopecten yessoensis. These four strains were identified as Pseudoalteromonas; however, they were phenotypically different from species described previously according to carbon compound utilization tests and the BIOLOG identification system. High agardecomposing activity was found in two strains, in one of which agarase, agalactosidase, pustulanase and laminarinase had been detected. The level of DNA homology of three of the strains was 70-100°/~. The fourth isolate was genetically less related to the others (67 O/ O DNA relatedness) and phenotypically was more distant from other members of this group; however, all four strains were assigned to a single species genotypically. DNA from the strains isolated from mussels showed 4 0 4 5 YO genetic relatedness with the DNA of Alteromonas atlantica, 8-36 YO with DNA of Pseudoalteromonas haloplanktis subsp. haloplanktis, Pseudoalteromon as haloplanktis subsp. tetraodonis, Pseudoalteromon as undina, Pseudoalteromon as nigrifaciens andPseudoalteromon as carrageenovora, 53 YO with Pseudoalteromon as elyakovii, 3 2 4 8 % with marine P. nigrifaciens from mussels and 14-16% with Alteromonas macleodii. The DNA-DNA hybridization data revealed that the levels of relatedness between the strains isolated and the type strains of Pseudoalteromonas citrea and Pseudoalteromonas fuliginea described recently were significant (95-85 YO). These results were confirmed by serological data employing polyclonal antibodies to cell surface antigens. The strains isolated from mussels were identified as P. citrea. The hybridization data showed that the name P. fuliginea Romanenko e t a / . 1994 should be recognized as a junior subjective synonym of P. citrea Gauthier 1977. A notable phenotypic diversity of P. citrea which might be a reflection of their ecological habitats is discussed. Keywords : marine bacteria, Pseudoalteromonas citrea INTRODUCTIONIntensive investigations stricted to a single species, Alteromonas macleodii, while a new genus, Pseudoalteromonas, was created for 13 other Alteromonas species. The latter are common of the genus Alteromonas during the last few years have led to revision and inhabitants of the aquatic environment, and were specification of its taxonomic structure on the one isolated mainly from sea water (8,14). Pseudohand (1, 2,14,15, 38), and broadening of the list of alteromonas strains, typically associated with marine species on the other (1 1, 12,24,33). The resulting data animals (16,29), might be of particular interest as a from small-subunit rDNA sequence analysis (1 5) promising source for new species with distinct features. revealed that the genus Alteromonas should be reOne such feature is a high hydrolytic activity, par- (v/v) distilled water at pH 7.5-743 as described elsewhere (19). Strains were maintained on the same semi-solid B medium in tubes und...

Nine nonpigmented strains of gram-negative, aerobic, marine bacteria with polar flagella were isolated from the mussels Crenomytilus grayanus and Patinopecten jessoensis. These organisms were conspecific and exhibited relatively high levels of genetic relatedness (61 to 100%). The G+C contents of the DNAs of these strains were 38.5 to 40.2 mol%. The strains isolated from mussels were phenotypically distinct from previously described Alteromonas species that have similar DNA G + C contents (Alteromonas haloplanktis, Alteromonas tetraodonis, Alteromonas atlantica, and Alteromonas carrageenovora), and their DNAs exhibited only 12 to 41% similarity with the DNAs of the type strains of these species. DNA-DNA hybridization data revealed that the levels relatedness between the strains which we studied and the type strain of AZteromonas nigrifaciens were significant (66 to 70%). Production of a melanin-like pigment, which is characteristic of A. nigrifaciens, was observed only in tyrosine-containing media. The strains isolated from mussels were identified as A. nigrifaciens. We present an emended description of A. nigrifaciens that includes several phenotypic and chemotaxonomic characteristics.The genus Alteromonas Baumann et al. 1972 includes both nonpigmented and pigmented gram-negative, aerobic, polarly flagellated, marine bacterial species (4, 5, 7, l l ) , and there have been numerous proposals of new Alteromonas species recently (3, 10,12,16,22). However, phenotypic discrimination of the species of this genus is problematic because of significant variations in their phenotypic traits. Phenotypic differences are frequently observed among even genetically closely related strains (2). Tests to determine utilization of specific carbon sources, which have been used successfully in Pseudomonas systematics (9), are less informative when they are used for differentiation of Alteromonas species. Some characteristics, such as requirements for growth factors and the production of pigments and some secondary metabolites, which were described as specific characteristics of certain species, have been shown to be strain-specific characteristics in recent studies. For example, one strain of Alteromonas tetraodonis produces tetrodotoxin, and recent investigations of the DNA relatedness of Alteromonas species have shown that A. tetraodonis is closely related genetically to Alteromonas haloplanktis, which never produces tetrodotoxin (10). Thus, genetic and chemotaxonomic methods appear to provide more reliable information than differential phenotypic characteristics in Alteromonas systematics.We previously isolated several strains belonging to the genus Alteromonas from the Far Eastern mussels Crenomytilus grayanus and Patinopecten jessoensis (13). The purpose of this study was to characterize and identify these strains by using phenotypic, genetic, and chemotaxonomic methods in order to provide additional taxonomic data for Alteromonas species. MATERIALS AND METHODSBacterial strains and isolation. The strains which we used are lis...

Two strains of agar-digesting bacteria, KMM 3299T and KMM 3300, respectively isolated from sea water and the mussel Protothaca jedoensis, have been characterized. Based on sequencing of the 16S rRNA gene, KMM 3299 T showed the highest similarity (93-95 %) to members of the genus Shewanella. The GMC contents of the DNAs of these strains were 43-44 mol %. The level of DNA homology between the two strains was conspecific (95 %), indicating that they represent a distinct genospecies. These organisms were non-pigmented, Gramnegative, polarly flagellated, facultatively anaerobic, mesophilic, neutrophilic and able to degrade a wide range of high molecular mass polymers, including alginate, carrageenan, laminaran and agar. The novel organisms were susceptible to gentamycin, carbenicillin, lincomycin and oleandomycin. The predominant cellular fatty acids were i-15 :0, 16 :0, 16 :1(n-7), 18 :1(n-7). Eicosapentaenoic acid, 20 :5(n-3), was detected in the two isolates at levels of 1-8 %, depending on the temperature of cultivation. Phylogenetic evidence, together with phenotypic characteristics, showed that the two isolates studied constitute a novel species of the genus Shewanella. The name Shewanella japonica is proposed ; the type strain is KMM 3299 The genus Shewanella MacDonell and Colwell 1986 currently comprises 12 species of Gram-negative, facultatively anaerobic proteobacteria, associated mainly with aquatic habitats. During the last decade, the bacteria of this genus have received a significant amount of attention due to their important roles in co-metabolic bioremediation of halogenated organic pollutants (Petrovskis et al., 1994), destructive souring of crude petroleum (Semple & Westlake, 1987) and the dissimilatory reduction of magnesium and iron oxides (Myers & Nealson, 1988). Recently, a comprehensive study of the phylogenetic relationships and taxonomy of the genus provided an improved approach for identification of newly isolated wild strains (Venkateswaran et al., 1999). In this study, a novel agar-digesting bacterium of the genus Shewanella is described, isolated from sea water and the mussel Protothaca jedoensis, dwelling in the coastal area of the Sea of Japan. The two isolates formed a distinct phylogenetic clade among other previously described shewanellae and constitute a new species.Sea water samples were collected in 1994 from a depth of 0n5-1n5 m (salinity, 32 =; temperature, 15 mC) at the Pacific Institute of Bio-organic Chemistry of the Marine Experimental Station, Troitza Bay, Gulf of Peter the Great, Sea of Japan. The mussels were collected at a depth of 3-5 m and were prepared aseptically as described elsewhere (Ivanova et al., 1996). All samples were plated onto marine 2216 agar or medium B, which contained 0n2% (w\v)

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Four light-yellow-pigmented, Gram-negative, short-rod-shaped, non-motile isolates were obtained from enrichment culture during degradation of the thallus of the brown alga Fucus evanescens. The isolates studied were chemo-organotrophic, alkalitolerant and mesophilic. Polar lipids were analysed and phosphatidylethanolamine was the only phospholipid identified. The predominant cellular fatty acids were 15 : 0, i15 : 0, ai15 : 0, i15 : 1 and 15 : 1(n-6). The DNA G+C contents of the four strains were 34?0-34?4 mol%. The level of DNA relatedness of the four isolates was conspecific (88-98 %), indicating that they belong to the same species. The 16S rDNA sequence of strain KMM 3553 T was determined. Phylogenetic analysis revealed that KMM 3553 T formed a distinct phyletic line in the phylum Bacteroidetes, class Flavobacteria in the family Flavobacteriaceae and that, phylogenetically, this strain could be placed almost equidistant from the genera Gelidibacter and Psychroserpens (16S rRNA gene sequence similarities of 94 %). On the basis of significant differences in phenotypic and chemotaxonomic characteristics, it is suggested that the isolates represent a novel species in a new genus; the name Formosa algae gen. nov., sp. nov. is proposed. The type strain is KMM 3553 T