Three strains of moderately thermophilic, sulfur-reducing bacteria were isolated from shallow-water hot vents of the Bay of Plenty (New Zealand) and Matupi Harbour (Papua New Guinea). Cells of all isolates were short, Gram-negative, motile rods with one polar flagellum. All strains were obligate anaerobes and grew optimally at pH 5.8-6.2, 52-54 °C and 2.5-3% (w/v) NaCI. Growth substrates were molecular hydrogen, acetate and saturated fatty acids; one of the strains, isolated from Matupi Harbour, was able to utilize ethanol. Elemental sulfur was required for growth. H2S and CO2 were the only growth products. No growth occurred in the absence of 100 mg yeast extract I−1. The G+C content of the DNA determined for the type strain MH2 T was 40.4 mol%. Results of 16S rDNA sequencing indicated that these strains represent a distinct lineage most closely related to the genus Desulfurella. On the basis of the results of morphological, physiological and phylogenetic studies, a new genus, Hippea gen. nov., is proposed with the type species Hippea maritima gen. nov., sp. nov., of which the type strain is MH2 T (= DSM 10411T).
The phylogenetic positions of two strains of fermentative bacteria that had been isolated from the highest positive tubes inoculated with serial dilutions of estuarine mud in agar media with either glutamate or aspartate as substrate were determined by comparative sequence analysis of their 16S rRNA genes. The strain isolated with glutamate (glu 65) utilized several substrates, including a number of amino acids but no sugars. The degradation of certain substrates was enhanced by or dependent upon co-cultivation with a hydrogen-utilizing partner. In earlier work this strain was assigned to the new genus and species Acidaminobacter hydrogenoformans. On the basis of its 16S rRNA gene sequence Acidaminobacter hydrogenoformans has now been identified as a member of cluster XI of the Clostridium subphylum with Clostridium halophilum as its closest relative. The aspartate-fermenting strain asp 66T was a Gram-negative, rather aerotolerant anaerobe which utilized a wide range of substrates in a propionic fermentation and had the ability to fix molecular nitrogen. Strain asp 66T was shown to be a new member of the ß-subclass of the Proteobacteria with Azoarcus sp. strain 6a3 and Rhodocyclus tenuis as its closest relatives. It is described as Propionibacter pelophilus gen nov., sp. nov., with the type strain asp 66T (= DSM 12018T).
A heterotrophic bacterial strain TL1T capable of aerobic denitrification was previously enriched in continuous culture from a landfill leachate treatment plant and isolated as a pure culture. The taxonomic position of this isolate within the ß-subclass of the Proteobacteria was determined by 16S rDNA sequence analysis and by conventional taxonomy including substrate spectrum, quinone type (ubiquinone Q-8) and cellular fatty acid composition. Detection of the specific polyamine 2-hydroxyputrescine supports the membership of strain TL1T in the ß-subclass of the Proteobacteria. The results of 16S rDNA sequencing showed that the strain clustered with, but was separate from, Thauera aromatica and Thauera selenatis. DNA-DNA hybridization experiments indicated that the new isolate represents a new species of the genus, for which the name Thauera mechernichensis is proposed; the type strain is DSM 12266T.
The genus Caulobacter is composed of prosthecate bacteria often specialized for oligotrophic environments. The taxonomy of Caulobacter has relied primarily upon morphological criteria: A strain that visually appeared to be a member of the Caulobacter has generally been called one without challenge. A polyphasic approach, comprising 16S rDNA sequencing, profiling restriction fragments of 16S-23S rDNA interspacer regions, lipid analysis, immunological profiling and salt tolerance characterizations, was used to clarify the taxonomy of 76 strains of the genera Caulobacter, Brevundimonas, Hyphomonas and Mycoplana. The described species of the genus Caulobacter formed a paraphyletic group with Caulobacter henricii, Caulobacter fusiformis, Caulobacter vibrioides and Mycoplana segnis (Caulobacter segnis comb, nov.) belonging to Caulobacter sensu stricto. Caulobacter bacteroides (Brevundimonas bacteroides comb, nov.), C. henricii subsp. aurantiacus (Brevundimonas aurantiaca comb, nov.), Caulobacter intermedius (Brevundimonas intermedia comb. nov.), Caulobacter subvibrioides (Brevundimonas subvibrioides comb. nov.), C. subvibrioides subsp. albus (Brevundimonas alba comb. nov.), Caulobacter variabilis (Brevundimonas variabilis comb. nov.) and Mycoplana bullata belong to the genus Brevundimonas. The halophilic species Caulobacter maris and Caulobacter halobacteroides are different from these two genera and form the genus Maricaulis gen. nov. with Maricaulis maris as the type specis Caulobacter leidyia was observed to cluster with species of the genus Sphingomonas. Caulobacter crescentus is synonymous with C.vibrioides and C. halobacteroides is synonymous with Maricaulis maris as determined by these analyses and DNA-DNA hybridization. Biomarkers discerning these different genera were determined. The necessary recombinations have been proposed and a description of Maricaulis is presented.
The taxonomic position of eight fluorescent Pseudomonas isolates, from two Lebanese spring waters, which were previously recognized by numerical analysis as members of a new subcluster (subcluster Vb) was examined. Excep for one strain, the new subcluster exhibited internal DNA hybridization values of 76-100%, and 9–53% hybridization was measured with the type or reference strains of other Pseudomonas species. The highest DNA binding value was found with Pseudomonas marginalis strains (37–53%). The G+C content of the DNA of the type strain was 58 mol%. A comparison of 1322 nt of the 16S rRNA gene sequence of the strain representing subcluster Vb (CFML 96–1951T) with the sequence of other strains of the genus Pseudomonas revealed that strain CFML 96–195T was part of the ‘Pseudomonas fluorescens intrageneric cluster’. On the basis of the results of phenotypic, DNA-DNA and phylogenetic analyses, a new Pseudomonas species, Pseudomonas libanensis sp. nov., is proposed for the seven strains of subcluster Vb. The type strain is P. libanensis CFML 96–195T and has been deposited in the Collection de I'lnstitut Pasteur (Paris, France) as CIP 105460T. The P. libanensis strains are phenotypically and genotypically homogeneous and can be differentiated from most other fluorescent species by several phenotypic features. Differentiation of P. libanensis and Pseudomonas aeruginosa is based mainly on pyocyanin production; P. libanensis can be differentiated from P. fluorescens (all biovars) by α-aminobutyrate assimilation. The clinical significance of P. libanensis is unknown.
[Pseudomonas] echinoides DSM 1805T (= ATTC 14820T, DSM 50409T, ICBP NCIB 9420T) has been reinvestigated to clarify its taxonomic position. 16 sequence comparisons demonstrated that this species clusters phylogenetically with species of the genus Sphingomonas. Investigation fatty acid patterns, polar lipid profiles, polyamine patterns and quinc systems supported this delineation. Substrate utilization profiles and biochemical characteristics displayed no distinct overall similarity to an validly described species of the genus Sphingomonas. Therefore, the reclassification of [Pseudomonas] echinoides as Sphingomonas echinoides comb. nov. is proposed, based upon the estimated phylogenetic positon derived from 16S rRNA gene sequence data, chemotaxonomic data and previously published genomic DNA G+C content data.
A taxonomic characterization of twenty-one strains capable of degrading aromatic compounds under denitrifying conditions, isolated from ten different geographical locations, was performed on the basis of general morphological and physiological characteristics, cellular fatty acids, DNA base composition, small ribosomal (16S) subunit DNA sequences, whole-cell protein patterns and genomic DNA fragmentation analysis, in addition to DNA similarity estimations using hybridization methods. The collection of strains was subdivided into a number of different groups. A first group, consisting of four strains, could be assigned to the previously described species Azoarcus tolulyticus. A second group (five strains) had DNA which reannealed highly to that of strains of the first group, and it is considered to represent a genomova of A. tolulyticus. The third and fourth groups, composed of a total of five strains, represent a new species of Azoarcus, Azoarcus toluclasticus (group 3) and a genomovar of this species (group 4), respectively. Finally, the fifth group, with two strains, corresponds to another new species of the genus Azoarcus, Azoarcus toluvorans. In addition to these five groups, the collection includes five individual strains perhaps representing as many different new species. The above classification is partially consistent with the results of approaches other than DNA-DNA hybridization (electrophoretic patterns of whole-cell proteins and of the fragments obtained after digestion of total DNA with infrequently cutting restriction enzymes). On the other hand, no correlation of these groupings was found in terms of the cellular fatty acid composition. It is also unfortunate that no simple sets of easily determinable phenotypic properties could be defined as being characteristic of each of the groups.
Two strains of dissimilatory arsenate-reducing vibrio-shaped bacteria are assigned to the genus Sulfurospirillum. These two new species, Sulfurospirillum barnesii strain SES-3T and Sulfurospirillum arsenophilum strain MIT-13T, in addition to Sulfurospirillum sp. SM-5, two strains of Sulfurospirillum deleyianum, and Sulfurospirillum arcachonense, form a distinct clade within the ε subclass of the Proteobacteria based on 16S rRNA analysis.
The polyphenol oxidase (PPO) activities of the marine melanogenic strains MMB-1T and 2–40 were compared. Both contained a multifunctional PPO able to oxidize a wide range of substrates. In spite of this similarity, phylogenetic studies based on 16S rRNA sequences showed that these strains are not closely related. Strain 2–40 is not related to any previously described genus. On the basis of these studies and morphological and physiological characteristics, it is proposed that strain MMB-1T (= CECT 4803T = ATCC 700492T) represents a new species in the genus Marinomonas, Marinomonas mediterranea sp. nov.