Biomedical subjects

Richard Christen

Publications and source records attributed to Richard Christen.

46 records · Page 3Linked to original sources

PubMed2002

Pseudoalteromonas maricaloris sp. nov., isolated from an Australian sponge, and reclassification of [Pseudoalteromonas aurantia] NCIMB 2033 as Pseudoalteromonas flavipulchra sp. nov.

A marine, gram-negative, aerobic bacterium that produced cytotoxic, lemon-yellow, chromopeptide pigments that inhibited the development of sea urchin eggs has been isolated from the Australian sponge Fascaplysinopsis reticulata Hentschel. The cells of the organism were rod-shaped with a single polar flagellum and they required NaCl for growth (0.5-10%) with optimum growth at 1-3% NaCl. The temperature for growth was 10-37 degrees C, with optimum growth at 25-30 degrees C. Growth occurred at pH values from 6.0 to 10.0, with optimum growth at pH 6.0-8.0. Major phospholipids were phosphatidylethanolamine, phosphatidylglycerol and lyso-phosphatidylethanolamine. Of 26 fatty acids with 11-19 carbon atoms that were detected, 16:1omega7, 16:0, 17:1omega8 and 18:1omega7 were predominant. The DNA G+C content was 38.9 mol%. All of these phenotypic and chemotaxonomic characters place the organism in the genus Pseudoalteromonas (Gauthier et al, 1995). These data are consistent with the phylogenetic analyses that confirmed that strain KMM 636T is a member of the Pseudoalteromonas cluster in the gamma-subclass of the Proteobacteria. DNA-DNA hybridization experiments revealed that the levels of relatedness between the DNA of the strain studied and DNAs of type strains of the species that clustered together (on the basis of 16S rDNA sequences) and [Pseudoalteromonas aurantia] NCIMB 2033 ranged from 19 to 35%, and that the DNA-DNA homology between [P. aurantia] NCIMB 2033 and other phylogenetically and/or phenotypically similar type strains ranged from 32 to 52%. According to the polyphasic evidence presented in this study, it is proposed that strain KMM 636T (= LMG 19692T = CIP 106859T) be classified as Pseudoalteromonas maricaloris sp. nov. and [P. aurantia] NCIMB 2033 be reclassified as Pseudoalteromonas flavipulchra NCIMB 2033T (= KMM 3630T = LMG 20361T) sp. nov.

Animals↗

PubMed2002

Pseudomonas lini sp. nov., a novel species from bulk and rhizospheric soils.

The taxonomic position of eight fluorescent Pseudomonas strains isolated from bulk and rhizospheric soils, and from water was examined. These eight strains clustered in one phenon together with Pseudomomas mandelii (CFBP 4844T), but could still be differentiated from this type strain by four phenotypic features. The eight stains exhibited internal DNA-DNA hybridization values ranging from 60 to 100%, with deltaTm below 5 degrees C (3.9 and 4.3 degrees C) for the lowest values (60 and 66%). The percentages of hybridization with type or reference strains of other Pseudomonas species tested ranged from 12 to 60% (deltaTm = 5.5 degrees C), indicating that the eight isolates studied constituted a discrete DNA homology group. Comparison of the 16S rDNA sequence of the strain representing this group (CFBP 5737T) with the sequences of other strains belonging to the genus Pseudomonas revealed that strain CFBP 5737T was a member of this genus and that these bacteria did not cluster with any previously described species of the genus Pseudomonas. The eight isolates belonged to two siderovars different from those described so far. On the basis of the results of phenotypic, DNA-DNA and phylogenetic analyses, and of siderotyping, a new species, Pseudomonas lini sp. nov. (type strain CFBP 5737T) is proposed.

DNA, Bacterial↗

PubMed2002

Phenotypic and genomic evidence for the revision of Pseudomonas corrugata and proposal of Pseudomonas mediterranea sp. nov.

To re-examine the taxonomic status of Pseudomonas corrugata, 27 strains of this species were studied using a polyphasic approach. Numerical analysis of phenotypic data revealed two phena, A (including the P. corrugata type strain) and B, which could be clearly differentiated by the assimilation of mesotartrate, 2-ketogluconate and histamine. The mean DNA reassociation values with labelled DNA of P. corrugata type strain CFBP 2431T (phenon A) and strain CFBP 5447T (phenon B) were high for strains belonging to the same phenon (96.9 and 98.5%, respectively), whereas the DNA relatedness between the two phena was assessed as being close to 70%, which represents the value that is accepted for the definition of a bacterial species. Phena A and B were also differentiated by means of DNA profiles generated by heteroduplex mobility assay of PCR products of 16S rDNA hypervariable region 2, HaeIII restriction of the amplified internal transcribed spacer, REP- and BOX-PCR profiles, and by PCR with two pairs of specific primers. A comparison of the 16S rRNA sequences of strains CFBP 5447T and CFBP 5458 from phenon B with the available sequences of Pseudomonas species showed that these strains formed a cluster distinct from the P. corrugata type strain. Thus, a new species, Pseudomonas mediterranea, is proposed for strains of phenon B. The type strain is strain CFBP 5447T (= ICMP 14184T); its G+C content is 60.2 mol%.

Base Composition↗

PubMed2002

Pseudoalteromonas translucida sp. nov. and Pseudoalteromonas paragorgicola sp. nov., and emended description of the genus.

On the basis of phenotypic and genotypic characteristics and analysis of 16S rRNA sequences, two novel species belonging to the genus Pseudoalteromonas are described. A pale-orange-pigmented strain, KMM 3548T, isolated from a sponge and a non-pigmented strain, KMM 520T, isolated from sea water are marine, gram-negative, aerobic, rod-shaped organisms. One of the strains, KMM 520T, had bipolar flagella. Both strains had the ability to degrade gelatin, DNA and Tween 80 but not chitin or agar. Strain KMM 520T decomposed elastin and grew at NaCl concentrations of 1-8%, while strain KMM 3548T grew at 1-6% NaCl. The temperature range for both strains was 4-30 degrees C. The DNA G+C contents were 46.3 (KMM 520T) and 41.1 mol% (KMM 3548T). The level of DNA relatedness between the two strains was 20%. DNA from strain KMM 520T showed 8-34% genetic relatedness and that of KMM 3548T showed 17-53% relatedness to the DNA of other type strains of the genus Pseudoalteromonas. 16S rRNA analysis indicated a clear affiliation of these novel bacteria with the genus Pseudoalteromonas. The type strains of the novel species are Pseudoalteromonas translucida sp. nov. KMM 520T (= LMG 19696T = ATCC BAA-3157T) and Pseudoalteromonas paragorgicola sp. nov. KMM 3548T (= LMG 19694T = ATCC BAA-322T).

Animals↗

PubMed2002

Rheinheimera baltica gen. nov., sp. nov., a blue-coloured bacterium isolated from the central Baltic Sea.

A set of taxonomically unique, blue-coloured bacterial isolates are described on the basis of physiological and biochemical characterization, fatty acid profiling and analyses of 16S rDNA sequences. The flagellated, non-fermentative strains were isolated in 1986, 1987 and 1998 from different layers of the water column of the central Baltic Sea. According to 16S rDNA sequences, all strains are very closely related to each other and to strains from several other marine environments, including the deep sea. Thus, the described species seems to be widespread in marine habitats. According to DNA-DNA hybridization, the strains described can be considered to belong to the same species. The bacteria grew at temperatures from 4 to 30 degrees C, with an optimum around 20-25 degrees C. Growth was observed at salinities from 0 to 30, with an optimum between 10 and 30 and no growth at high salinities. The dominant fatty acids were 16:1omega7c, 16:0 and 18:1omega7c. The G+C content of the DNA ranged from 47.8 to 48.9 mol%. Phylogenetic analyses of the 16S rDNA sequences revealed a clear affiliation with members of the gamma-Proteobacteria. The closest relationship was seen with Alishewanella fetalis but, in terms of physiology, colour and fatty acids, the bacteria described are rather distant from A. fetalis. To honour the marine microbiologist Gerhard Rheinheimer, the name Rheinheimera baltica gen. nov., sp. nov., is suggested for the Baltic isolates, with the type strain OSBAC1T (= DSM 14885T = LMG 21511T).

Baltic States↗

PubMed2002

Pseudomonas costantinii sp. nov., another causal agent of brown blotch disease, isolated from cultivated mushroom sporophores in Finland.

Pathogenic bacteria are frequently associated with mushroom sporophores exhibiting brown blotch disease symptoms. These bacteria belong mainly to Pseudomonas tolaasii or occasionally to 'Pseudomonas reactans'. Although a group of isolates originating from some Finnish mushroom farms satisfied the two characteristic criteria for diagnosis of infection with P. tolaasii (i.e. yielding a typical brown blotch symptom on Agaricus bisporus sporophores and producing a typical white line in agar when streaked towards the 'P. reactans' LMG 5329 inducing strain), results based on numerical taxonomy, siderotyping, DNA-DNA hybridizations and 16S rDNA phylogenetic analyses supported the view that these isolates constituted a novel species within the genus Pseudomonas, Pseudomonas costantinii. The type strain is PS 3a(T) (= CFBP 5705(T) = HAMBI 2444(T)).

Agaricus↗

PubMed2002

Pseudomonas salomonii sp. nov., pathogenic on garlic, and Pseudomonas palleroniana sp. nov., isolated from rice.

A total of 26 strains, including 15 strains isolated from garlic plants with the typical symptoms of 'Café au lait' disease and 11 strains isolated from diseased or healthy rice seeds and sheaths infested by Pseudomonas fuscovaginae, were compared with 70 type or reference strains of oxidase-positive pathogenic or non-pathogenic fluorescent pseudomonads. The strains were characterized by using a polyphasic taxonomic approach. Numerical taxonomy of phenotypic characteristics showed that the garlic and rice strains were related to each other. However, they clustered into separate phenons, distinct from those of the other strains tested, and were different in several nutritional tests. On the basis of DNA-DNA hybridization, the garlic and rice strains constituted two distinct DNA hybridization groups, indicating that they belonged to separate species. The two groups of strains were also well differentiated by siderotyping. Garlic strains were pathogenic to garlic plants and either weakly pathogenic or non-pathogenic on rice; rice strains were either weakly pathogenic or non-pathogenic on rice and non-pathogenic on garlic. A phylogenetic analysis of 16S rRNA gene sequences confirmed that the two groups of strains belonged to the y-Proteobacteria and to the genus Pseudomonas. The names Pseudomonas salomonii sp. nov. and Pseudomonas palleroniana sp. nov. are respectively proposed for the garlic strains and the rice strains. The type strains are P. salomonii CFBP 2022(T) ( = ICMP 14252(T) = NCPPB 4277(T)) and P. palleroniana CFBP 4389(T) (= ICMP 14253(T) = NCPPB 4278(T)).

Base Composition↗

PubMed2002

Pseudomonas extremorientalis sp. nov., isolated from a drinking water reservoir.

On the basis of phenotypic and genotypic characteristics and 16S rDNA sequence analysis, a novel species belonging to the genus Pseudomonas sensu stricto was identified. The saprophytic, fluorescent bacterium, designated KMM 3447(T), was isolated from a drinking water reservoir near Vladivostok City, Russia. The novel organism was a Gram-negative, aerobic, rod-shaped bacterium that produced a cyclic depsipeptide with surface-active properties. It degraded casein, but did not degrade gelatin, starch, agar or Tween 80. The bacterium was also haemolytic. Growth of the novel bacterium occurred between 4 and 35 degrees C. The predominant cellular fatty acids of the novel pseudomonad were C16:0, C16:1(n-7), C18:1(n-7) and C17.0 cyclo; branched fatty acids were only found in trace amounts. The G+C content of the novel bacterium was 61.0 mol%. 16S rDNA sequence analysis indicated that the novel bacterium had a clear affiliation with Pseudomonas fluorescens and species closely related to this recognized pseudomonad. DNA-DNA hybridization experiments showed that the novel bacterium bound at low levels (27-53%) with the DNA of the type strains of its nearest phylogenetic relatives, namely Pseudomonas tolaasii, Pseudomonas veronii, Pseudomonas orientalis and Pseudomonas rhodesiae, indicating that the novel bacterium represented a novel species within the genus Pseudomonas, for which the name Pseudomonas extremorientalis is proposed; the type strain is KMM 3447(T) (= LMG 19695(T)).

Base Composition↗

PubMed2002

Shewanella denitrificans sp. nov., a vigorously denitrifying bacterium isolated from the oxic-anoxic interface of the Gotland Deep in the central Baltic Sea.

Three strains of denitrifying estuarine bacteria, OS217(T), 05220 and OS226, were characterized for their physiological and biochemical features, fatty acid profiles and their phylogenetic position based on 16S rDNA sequences. The strains were isolated from the oxic-anoxic interface of an anoxic basin of the central Baltic Sea. Phylogenetic analyses of the 16S rDNA sequences revealed a clear affiliation with members of the genus Shewanella of the gamma-Proteobacteria. The closest sequence similarity was seen with Shewanella baltica, Shewanella putrefaciens and Shewanella frigidimarina (95-96%). The dominant fatty acids were 16:1omega7c, 15:0 iso, 16:0 and 13:0 iso. The G+C content of the DNA ranged from 46.8 to 48.1 mol%. The strains were unpigmented, polarly flagellated, mesophilic, facultatively anaerobic and able to use nitrate, nitrite and sulphite as electron acceptors. Growth was observed at salinities from 0 to 6%, with an optimum between 1 and 3%. According to their morphology, physiology, fatty acid composition and 16S rRNA sequences, the described bacteria fitted well into the genus Shewanella, but could be easily distinguished from the Shewanella species described to date. Because of their capacity for vigorous denitrification, the name Shewanella denitrificans sp. nov. is suggested for the Baltic isolates, for which the type strain is OS217(T) (= DSM 15013(T) = LMG 21692(T)).

Baltic States↗

PubMed1996

Aseptic meningitis after neurosurgery: a demonstration of bacterial involvement.

OBJECTIVE: To evaluate the presence of bacteria in samples from patients suffering from 'aseptic' meningitis following craniotomy. METHODS: Prospective study in which cerebrospinal fluid (CSF) from patients suffering from post-craniotomy meningitis and negative control patients were submitted to conventional culture and to polymerase chain reaction (PCR) using bacterial 16S rRNA universal primers, followed in some cases by DNA sequencing of the PCR product and phylogenetic analysis. RESULTS: CSF from patients with either culture-positive or culture-negative meningitis yielded positive amplifications, whereas no amplification was obtained with CSF from control patients. All positive signals were confirmed by Southern hybridization with a prokaryote 16S RNA-specific probe. Six PCR products, of which three were collected from later cases of culture-negative meningitis, were cloned and sequenced. Sequence analysis suggested affinities with Pseudomonas in three cases, with Escherichia in two cases and with Rhodococcus in one case. CONCLUSIONS: Many cases of culture-negative (aseptic) meningitis are probably bacterial meningitis and justify antibiotic treatment. The bacteria responsible for these cases of culture-negative meningitis might have peculiar growth requirements in vitro.

Journal Article↗