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A taxonomic study was performed on 26 strains isolated from microbial mats in Antarctic lakes of the Vestfold Hills and the McMurdo Dry Valleys. Phylogenetic analysis based on 16S rRNA gene sequences placed these strains within the Rhodobacter group of the α-subclass of the Proteobacteria. Sequence similarity values for the strains with their nearest phylogenetic neighbours (Jannaschia, Octadecabacter and Ketogulonicigenium) ranged between 94·0 and 95·8 %. DNA–DNA hybridizations and comparison of repetitive extragenic palindromic DNA–PCR (rep-PCR) fingerprinting patterns revealed that these strains are members of three distinct species. The isolates are Gram-negative, chemoheterotrophic, non-motile rods and their DNA G+C contents range from 59·4 to 66·4 mol%. Whole-cell fatty acid profiles are similar and the primary fatty acid in all the strains is 18 : 1 ω7c (74·1–87·7 % of total). Genotypic results together with phenotypic characteristics allowed the differentiation of these species from related recognized species of the α-Proteobacteria and the strains are assigned to a new genus, Loktanella gen. nov., with three novel species: Loktanella salsilacus sp. nov. (type species), consisting of ten strains with LMG 21507T (=CIP 108322T) as type strain; Loktanella fryxellensis sp. nov., consisting of 12 strains with LMG 22007T (=CIP 108323T) as type strain; and Loktanella vestfoldensis sp. nov., consisting of four strains with LMG 22003T (=CIP 108321T) as type strain.

Three Arcobacter isolates, recovered from mussels (genus Mytilus), and one isolate from brackish water in Catalonia (north-east Spain) showed a novel pattern using a recently described identification method for members of the genus Arcobacter, 16S rRNA gene RFLP. Enterobacterial repetitive intergenic consensus PCR fingerprinting demonstrated that the three isolates from mussels belonged to two genotypes and that the fourth isolate from water belonged to a third genotype. Analysis of the 16S rRNA and rpoB gene sequences showed that the new isolates formed a separate lineage within the genus Arcobacter. This was also confirmed by the low DNA-DNA relatedness values (16-30%) of the isolates with the type strains of recognized Arcobacter species. Hydrolysis of indoxyl acetate, a characteristic trait for all species of the genus Arcobacter, was negative for the novel isolates. The susceptibility of the novel isolates to cefoperazone, together with the lack of urease production and nitrate reduction, further enabled them to be differentiated from recognized Arcobacter species based on physiological characteristics. Genotypic and phenotypic characteristics indicated that the new isolates represent a novel species of the genus Arcobacter, for which the name Arcobacter mytili sp. nov. is proposed, with the type strain F2075(T) (=CECT 7386(T) =LMG 24559(T)). The DNA G + C content of strain F2075(T) was 26.9 mol%

Seven novel, cold-adapted, strictly aerobic, facultatively oligotrophic strains, isolated from Antarctic sea water, were investigated by using a polyphasic taxonomic approach. The isolates were Gram-negative, chemoheterotrophic, motile, rod-shaped cells that were psychrotolerant and moderately halophilic. Buds were produced on mother and daughter cells and on prosthecae. Prostheca formation was peritrichous and prosthecae could be branched. Phylogenetic analysis based on 16S rRNA gene sequences indicated that these strains belong to the c-Proteobacteria and are related to the genus Alteromonas, with 98?3 % sequence similarity to Alteromonas macleodii and 98?0 % to Alteromonas marina, their nearest phylogenetic neighbours. Whole-cell fatty acid profiles of the isolates were very similar and included C 16 : 0 , C 16 : 1 v7c, C 17 : 1 v8c and C 18 : 1 v8c as the major fatty acid components. These results support the affiliation of these isolates to the genus Alteromonas. DNA-DNA hybridization results and differences in phenotypic characteristics show that the strains represent a novel species with a DNA G+C content of 43-45 mol%. The name Alteromonas stellipolaris sp. nov. is proposed for this novel species; the type strain is ANT 69a T (=LMG 21861). An emended description of the genus Alteromonas is given.The genus Alteromonas belongs to the c-Proteobacteria and was created by Baumann et al. (1972) for marine, Gramnegative, heterotrophic bacteria that are motile by a single, polar flagellum. On the basis of 16S rDNA sequence analysis, the genus was revised in 1995 to contain a single species, Alteromonas macleodii, and the remaining species were reclassified as Pseudoalteromonas (Gauthier et al., 1995). In 1993, the yellow-grey-pigmented species 'Alteromonas rava', which is able to produce a novel antibiotic, was described (Kodama et al., 1993), but the species name has not yet been validly published. A mesophilic, heterotrophic bacterium, isolated from sea water that was collected near a deep-sea hydrothermal vent, was identified as A. macleodii, but it was classified as a novel subspecies, 'A. macleodii subsp. fijiensis', on the basis of a relatively low DNA-DNA hybridization level (<90 %, but >70 %), metabolic differences between the type strain and the novel strain, the ability of the novel bacterium to produce a unique exopolysaccharide and the isolation source (Raguénès et al., 1996). The subspecies name 'A. macleodii subsp. fijiensis'has not yet been validly published. Raguénès et al. (1997) proposed a novel Alteromonas species, 'Alteromonas infernus', for a polysaccharide-producing bacterium that was isolated from the surface of the vestimentiferan worm Riftia pachyptila, which inhabits sites near hydrothermal vents. The name of this novel species, however, has also not been validly published. Romanenko et al. (1994) described a novel species, Alteromonas fuliginea, but phylogenetic analysis based on 16S rDNA sequence data revealed that this species is related more closely to Pseudoalteromonas haloplank...

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Twenty-two isolates from microbial mats in eastern Antarctic lakes showed similar fatty acid compositions and were investigated further using a polyphasic taxonomic approach. Repetitive extragenic palindromic DNA-PCR fingerprinting of the 22 strains revealed three groups, and DNA-DNA hybridizations between representatives showed more than 87 % DNA-DNA reassociation with each other. 16S rRNA gene sequence analysis placed two representative strains, LMG 21477 T and LMG 21619, within the genus Flavobacterium, with 95?1 % sequence similarity to Flavobacterium flevense, 95?0 % to Flavobacterium tegetincola, less than 95 % to other Flavobacterium species and less than 90 % to representatives of other genera. The name Flavobacterium gelidilacus sp. nov. is proposed, with LMG 21477 T (=DSM 15343 T ) as the type strain, and a description of the species is given on the basis of morphological, biochemical and physiological characteristics and fatty acid composition. The G+C content of the genomic DNA is 30?0-30?4 mol%.Members of the genus Flavobacterium have been isolated from diverse habitats such as fresh water (Flavobacterium aquatile, Flavobacterium flevense, Flavobacterium hibernum, Flavobacterium saccharophilum), soil (Flavobacterium johnsoniae, Flavobacterium pectinovorum, Flavobacterium xanthum) and sea ice (Flavobacterium gillisiae); some are known as important fish pathogens (Flavobacterium branchiophilum, Flavobacterium columnare, Flavobacterium psychrophilum). They are abundant in freshwater and marine ecosystems, and these heterotrophic bacteria may have a specialized role in the uptake and degradation of the highmolecular-mass fraction of dissolved organic matter in these environments (Kirchman, 2002).Several novel species, added to the genus since 1996, were derived from Antarctic habitats, and several new genera containing polar organisms have recently been described within the family Flavobacteriaceae (Gelidibacter, Psychroserpens, Polaribacter, Psychroflexus, Salegentibacter). So far, only one species, Flavobacterium tegetincola, has been isolated from a cyanobacterial mat, collected from the Antarctic saline Ace Lake, located in the Vestfold Hills (McCammon & Bowman, 2000).During the MICROMAT project (November 1998 to February 2001), 746 bacterial strains were isolated under heterotrophic conditions from microbial mat samples, collected from 10 Antarctic lakes in the Vestfold Hills (lakes Ace, Druzhby, Grace, Highway, Pendant, Organic and Watts), the Larsemann Hills (Lake Reid) and the McMurdo Dry Valleys (lakes Hoare and Fryxell) (Van Trappen et al., 2002). Numerical analysis of their fatty acid composition revealed 41 clusters, and 16S rRNA gene sequence analysis, performed on representative strains, showed that they belong to the a-, b-and c-subclasses of the Proteobacteria, the high-and low-G+C-content Gram-positives and to the Cytophaga-Flavobacterium-Bacteroides branch (Van Trappen et al., 2002). The results of fatty acid analysis and 16S rRNA gene sequence analysis showed that the diversity of het...

A Gram-negative, rod-shaped, non-spore-forming and nitrogen-fixing bacterium, designated ICB 89 T , was isolated from stems of a Brazilian sugar cane variety widely used in organic farming. 16S rRNA gene sequence analysis revealed that strain ICB 89 T belonged to the genus

Taxonomic studies were performed on 36 strains that were isolated from microbial mats in Antarctic lakes of the Vestfold Hills, the Larsemann Hills and the McMurdo Dry Valleys. Phylogenetic analysis based on 16S rRNA gene sequences indicated that these strains are related to members of the genus Flavobacterium; sequence similarity values with their nearest phylogenetic neighbours ranged from 96·8 to 98·5 %. Results of DNA–DNA hybridization and comparison of repetitive extragenic palindromic DNA-PCR fingerprinting patterns revealed that these strains are members of three distinct species. Genotypic results, together with phenotypic characteristics, allowed the differentiation of these species from related Flavobacterium species with validly published names. The isolates are Gram-negative, chemoheterotrophic, rod-shaped cells that are psychrophilic and moderately halotolerant; their DNA G+C contents range from 33·1 to 34·5 mol%. Their whole-cell fatty acid profiles are similar and include C15 : 0, anteiso-C15 : 0, iso-C15 : 0, C15 : 1 ω6c, iso-C16 : 0, iso-C16 : 0 3-OH and summed feature 3 (which comprises iso-C15 : 0 2-OH, C16 : 1 ω7c or both) as major fatty acid components. On the basis of these results, three novel species are proposed, namely Flavobacterium degerlachei sp. nov. (consisting of 14 strains, with LMG 21915T=DSM 15718T as the type strain), Flavobacterium micromati sp. nov. (consisting of three strains, with LMG 21919T=CIP 108161T as the type strain) and Flavobacterium frigoris sp. nov. (consisting of 19 strains, with LMG 21922T=DSM 15719T as the type strain).