Three strains of psychrophilic bacteria isolated from Antarctic coastal marine environments were studied to determine their taxonomic position. These bacteria were Gram-negative rods, facultatively anaerobic and motile by means of a single polar flagellum. None of the bacterial isolates had an Na M requirement. Only one of the strains was capable of producing H 2 S from thiosulfate. The DNA base content of these bacteria was 41-42 mol % GMC. DNA-DNA hybridization experiments showed that the isolates formed two related groups that exhibited about 70 and 24 % DNA-DNA homology, respectively, with the type strain of Shewanella frigidimarina. The fatty acid profiles of the bacterial isolates were similar to the profiles of other Shewanella species. All the strains contained both ubiquinones and menaquinones, like Shewanella species. Methylmenaquinones were also found. 16S rRNA gene analysis confirmed that isolated strains belonged to the genus Shewanella and were phylogenetically related to the newly identified Shewanella frigidimarina. The results of the polyphasic taxonomic study assigned the three isolates to Shewanella and two of them specifically to Shewanella frigidimarina. INTRODUCTIONThe genus Shewanella was first described 14 years ago by MacDonell & Colwell (1985). The definition of Shewanella was based almost entirely on rRNA structure and included only the description ' straight or curved rods, Gram-negative, non-pigmented, motile by polar flagella, chemo-organotrophic, oxidasepositive, generally associated with aquatic or marine habitats. GjC mol % 44-47 '. The species Shewanella putrefaciens (Derby & Hammer, 1931 ; Lee et al., 1977) and Shewanella hanedai (Jensen et al., 1980) Abbreviation : TMAO, trimethylamine N-oxide.The EMBL accession numbers for the 16S rDNA gene sequence of strains NF12 and NF22 T are AJ300833 and AJ300834, respectively. included in the genus Shewanella, nine of which have been described in the last 3 years. Although the development of this bacterial group, from a taxonomic point of view, has taken place in the last decade, Shewanella putrefaciens has been studied since its first description as Achromobacter putrefaciens by Derby & Hammer (1931), because of its special interest in the areas of applied and environmental microbiology.Shewanella putrefaciens, first isolated as Achromobacter putrefaciens from rancid butter, was classified in 1960 as Pseudomonas putrefaciens by Shewan et al. (1960) and, later, as Alteromonas putrefaciens by Lee et al. (1977). This micro-organism has been found to be associated with the spoilage of proteinaceous foods (Shewan, 1977). Shewanella species are widely distributed and have been isolated from diverse sources such as aquatic environments (Nealson et al., 1991), sediments (Myers & Nealson, 1988), oilfield fluids Nu! ria Bozal and others (Semple & Westlake, 1987) and, as mentioned above, spoilage of proteinaceous foods (Levin, 1972 ;Shewan, 1974 ;Parker & Levin, 1983 ;Stenstrom & Molin, 1990), and are considered opportunistic pathogens...

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An endospore-forming strain, 20CM T , was isolated from Antarctic sediment and identified as a member of the genus Paenibacillus on the basis of phenotypic and phylogenetic analyses.

During the taxonomic investigation of cold-adapted bacteria from samples collected in the Antarctic area of the South Shetland Islands, one Gram-reaction-negative, psychrotolerant, aerobic bacterium, designated strain M1T , was isolated from marine sediment collected on

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Two Gram-negative, cold-adapted, moderately halophilic, aerobic bacteria, designated strains M3B T and M3T, were isolated from marine sediment collected from the South Shetland Islands, Antarctica. The organisms were rod-shaped, catalase-and oxidase-positive, and motile by means of polar flagella. These two psychrotolerant strains required Na + and grew at NaCl concentrations of 1-15 % and temperatures between 4 and 42 6C. 16S rRNA gene sequence analysis placed strains M3B T and M3T within the genus Marinobacter. DNA-DNA hybridization experiments between the Antarctic isolate M3B T and type strains of phylogenetically related species, namely Marinobacter lipolyticus, Marinobacter flavimaris, Marinobacter sediminum, Marinobacter algicola, Marinobacter maritimus and Marinobacter koreensis, revealed levels of relatedness lower than 32 %. Strain M3T showed 99 % DNA relatedness to strain M3B T . The DNA G+C contents of M3B T and M3T were 57.1 and 57.4 mol%, respectively, and their major isoprenoid quinone was ubiquinone-9. Several phenotypic characteristics, together with data on cellular fatty acid composition, served to differentiate strains M3B T and M3T from strains of related Marinobacter species. On the basis of the polyphasic taxonomic evidence presented in this study, it can be concluded that strains M3B T and M3T belong to the same genospecies and represent a novel species of the genus Marinobacter, for which the name Marinobacter guineae sp. nov. is proposed. The type strain is M3B T (5LMG 24048 T 5CECT 7243 T ).The genus Marinobacter, first established by Gauthier et al. (1992), belongs to the Gammaproteobacteria and comprises moderate halophilic bacteria from marine-related environments. At the time of writing, this genus included 16 species. During a taxonomic investigation of cold-adapted bacteria from samples collected in the Antarctic area of the South Shetland Islands, two strains, M3B T and M3T, were isolated that were able to grow at 15 u C on marine agar (MA; Difco), but not on tryptic soy agar (TSA; Difco). In this study, the taxonomic status of these two strains was investigated by using a combination of phenotypic characterization, 16S rRNA gene sequencing, DNA G+C content determination, DNA-DNA hybridization, and cellular fatty acid and isoprenoid quinone analysis.Strains M3B T and M3T were isolated from a marine sediment collected from Deception Island (South Shetland Islands, Antarctica). Sample aliquots were removed with a platinum loop and diluted in a saline solution (pH 7) containing the following salts (g l 21 ): 0.56, NaCl; 0.027, KCl; 0.03, CaCl 2 ; 0.01, NaHCO 3 . MA and TSA plates (both Difco) were inoculated with loopfuls of several sample dilutions by using the streak-plate method to obtain isolated colonies. Plates were incubated for 7 days at 15 u C. Growth was observed only on MA. Isolates were maintained aerobically on MA slopes at 4 u C and also at 280 u C on cryo-beads (AES Laboratoire).Morphology, cell size and shape of cells grown on MA at 15 u C were determined by means o...

Two strains of psychrotolerant bacteria, designated M7T and M5, isolated from Antarctic coastal marine environments were studied to determine their taxonomic position.