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...
