ABSTRACT
The taxonomic position of the misclassified strains [Flexibacter] tractuosus KCTC 2958T and '[Microscilla] sericea' LMG 13021 was studied using a polyphasic approach. The two strains shared 99.1% 16S rRNA gene sequence similarity and 28% DNA-DNA relatedness. On the basis of the phylogenetic evidence supported by genotypic and phenotypic data [Flexibacter] tractuosus KCTC 2958T and '[Microscilla] sericea' LMG 13021 are classified as two distinct species in a novel genus, Marivirga, in the family 'Flammeovirgaceae', as Marivirga tractuosa comb. nov. and Marivirga sericea nom. rev., comb. nov., with strains KCTC 2958T (=ATCC 23168T =CIP 106410T =DSM 4126T =NBRC 15989T =NCIMB 1408T =VKM B-1430T) and LMG 13021T (=ATCC 23182T =NBRC 15983T =NCIMB 1403T), respectively, as the type strains. The type species is Marivirga tractuosa.
Subject(s)
Bacteroidetes/classification , Flexibacter/classification , Bacteroidetes/genetics , Bacteroidetes/isolation & purification , DNA, Bacterial/genetics , DNA, Ribosomal/genetics , Flexibacter/genetics , Flexibacter/isolation & purification , Molecular Sequence Data , Phylogeny , RNA, Ribosomal, 16S/geneticsABSTRACT
A Gram-negative bacterium, designated strain LMG 22510T, was isolated from water of a pharmaceutical company steam generator. The cells had a ring-like and horseshoe-shaped morphology and possessed gliding motility. Phylogenetic analysis of the 16S rRNA gene sequence showed that the strain was a member of the Flexibacter group within the phylum 'Bacteroidetes'; its nearest neighbour was Spirosoma linguale (88.8 % sequence similarity). DNA base content, fatty acid composition and biochemical characteristics were determined. Genotypic and phenotypic data indicated that strain LMG 22510T could not be assigned to any recognized genus; therefore, a novel genus and species is proposed, Larkinella insperata gen. nov., sp. nov., with LMG 22510T (= NCIMB 14103T) as the type strain.
Subject(s)
Flexibacter/classification , Water Microbiology , Base Composition , Drug Industry , Fatty Acids , Flexibacter/chemistry , Flexibacter/isolation & purification , Flexibacter/physiology , Molecular Sequence Data , RNA, Bacterial/genetics , RNA, Ribosomal, 16S/genetics , Sequence Homology, Nucleic Acid , Species Specificity , SteamABSTRACT
A microbial consortium (AM) obtained by sequential enrichment in liquid culture with a polycyclic aromatic hydrocarbon (PAH) mixture of three- and four-ringed PAHs as a sole source of carbon and energy was examined using a triple-approach method based on various cultivation strategies, denaturing gradient gel electrophoresis (DGGE), and the screening of 16S and 18S rRNA gene clone libraries. Eleven different sequences by culture-dependent techniques and seven by both DGGE and clone libraries were obtained. The comparison of three variable regions (V3-V5) of the 16S rRNA gene between the sequences obtained yielded 19 different microbial components. Proteobacteria were the dominant group, representing 83% of the total, while the Cytophaga-Flexibacter-Bacteroides group (CFB) was 11% and the Ascomycota fungi 6%. Beta-proteobacteria were predominant in the DGGE and clone library methods, whereas they were a minority in culturable strains. The highest diversity and number of noncoincident sequences were achieved by the cultivation method that showed members of the alpha-, beta-, and gamma-Proteobacteria; CFB bacterial group; and Ascomycota fungi. Only six of the 11 strains isolated showed PAH-degrading capability. The bacterial strain (AMS7) and the fungal strain (AMF1), which were similar to Sphingomonas sp. and Fusarium sp., respectively, achieved the greatest PAH depletion. The results indicate that polyphasic assessment is necessary for a proper understanding of the composition of a microbial consortium.
