pmoA-based analysis of methanotrophs in a littoral lake sediment reveals a diverse and stable community in a dynamic environment.
(1/23)
Diversity and community structure of aerobic methane-oxidizing bacteria in the littoral sediment of Lake Constance was investigated by cloning analysis and terminal restriction fragment length polymorphism (T-RFLP) fingerprinting of the pmoA gene. Phylogenetic analysis revealed a high diversity of type I and type II methanotrophs in the oxygenated uppermost centimeter of the sediment. T-RFLP profiles indicated a high similarity between the active methanotrophic community in the oxic layer and the inactive community in an anoxic sediment layer at a 10-cm depth. There were also no major changes in community structure between littoral sediment cores sampled in summer and winter. By contrast, the fingerprint patterns showed substantial differences between the methanotrophic communities of littoral and profundal sediments. (+info)
Clinical significance of Roseomonas species isolated from catheter and blood samples: analysis of 36 cases in patients with cancer.
(2/23)
This report analyzes 36 cases of bacteremia or catheter-related infection caused by Roseomonas species, a group of pink, slimy, waterborne, gram-negative coccobacilli. The causative species included the newly described Roseomonas mucosa (22 cases [61%]) and Roseomonas gilardii subspecies rosea (8 cases [22%]) and known species R. gilardii subspecies gilardii (5 cases [14%]) and Roseomonas genomospecies 4 (1 case [3%]). Twenty-nine (81%) of the cases were symptomatic, with fever being the most common symptom (in 27 [75%] of the cases). Twenty (56%) of the infections were monomicrobic. Six cases (17%) involved persistent catheter colonization, and 5 of these cases required removal of the catheter to clear the infection. All infections resolved, most with empirical antibiotic treatment. A summary of the antibiotic susceptibility pattern of these strains and other reported series show that Roseomonas species are consistently susceptible to amikacin and imipenem and frequently susceptible to ciprofloxacin and ticarcillin, but essentially nonsusceptible to ceftazidime and cefepime. This result may guide future therapy for infections due to Roseomonas species. (+info)
Roseomonas lacus sp. nov., isolated from freshwater lake sediment.
(3/23)
An aerobic, Gram-negative bacterial strain, TH-G33T, was isolated from freshwater sediment of Taihu Lake in China. The taxonomy of strain TH-G33T was studied by using phenotypic and phylogenetic methods. Cells of strain TH-G33T were coccoid rods or rods and formed colourless to pale-pink colonies on nutrient agar. Phylogenetic analysis based on nearly complete 16S rRNA gene sequences showed that strain TH-G33T was related to Roseomonas mucosa (94.4 %), Roseomonas gilardii subsp. gilardii (94.1 %), Roseomonas gilardii subsp. rosea (94.8 %) and Roseomonas cervicalis (93.9 %). Cells contained ubiquinone 10 (Q-10) as the major quinone and the G+C content was 71.9 mol%. Thus, strain TH-G33T represents a novel species of the genus Roseomonas, for which the name Roseomonas lacus sp. nov. is proposed. The type strain is TH-G33T (= CGMCC 1.3617T = JCM 13283T). (+info)
Central line-related bacteraemia due to Roseomonas mucosa in a neutropenic patient with acute myeloid leukaemia in Piraeus, Greece.
(4/23)
A case of central venous catheter-related bacteraemia due to Roseomonas mucosa in a neutropenic patient with acute myelogenous leukaemia is reported. The patient was successfully treated with amikacin and piperacillin-tazobactam. The clinical isolate was identified as R. mucosa by 16S rRNA gene sequencing. (+info)
Roseomonas aquatica sp. nov., isolated from drinking water.
(5/23)
Strain TR53(T), a Gram-negative, non-motile, non-spore-forming and strictly aerobic coccobacillus, isolated from the drinking water distribution system of Seville, Spain, was subjected to polyphasic taxonomic analysis using a combination of phenotypic, genotypic and phylogenetic features. Phylogenetic analysis of 16S rRNA gene sequences showed that strain TR53(T) had highest similarity to members of the genus Roseomonas, with sequence similarity values between 95.7 % (to Roseomonas genomospecies 5 strain ATCC 49960) and 94.0 % (to Roseomonas gilardii subsp. rosea ATCC 49956(T)). On the basis of its phenotypic characteristics, 16S rRNA gene sequence data and DNA G+C content (68.6 mol%), strain TR53(T) represents a novel species of the genus Roseomonas, for which the name Roseomonas aquatica sp. nov. is proposed. The type strain of Roseomonas aquatica is TR53(T) (=CECT 7131(T)=JCM 13556(T)). (+info)
Nutrient amendments in soil DNA stable isotope probing experiments reduce the observed methanotroph diversity.
(6/23)
Stable isotope probing (SIP) can be used to analyze the active bacterial populations involved in a process by incorporating 13C-labeled substrate into cellular components such as DNA. Relatively long incubation times are often used with laboratory microcosms in order to incorporate sufficient 13C into the DNA of the target organisms. Addition of nutrients can be used to accelerate the processes. However, unnatural concentrations of nutrients may artificially change bacterial diversity and activity. In this study, methanotroph activity and diversity in soil was examined during the consumption of 13CH4 with three DNA-SIP experiments, using microcosms with natural field soil water conditions, the addition of water, and the addition of mineral salts solution. Methanotroph population diversity was studied by targeting 16S rRNA and pmoA genes. Clone library analyses, denaturing gradient gel electrophoresis fingerprinting, and pmoA microarray hybridization analyses were carried out. Most methanotroph diversity (type I and type II methanotrophs) was observed in non-amended SIP microcosms. Although this treatment probably best reflected the in situ environmental conditions, one major disadvantage of this incubation was that the incorporation of 13CH4 was slow and some cross-feeding of 13C occurred, thereby leading to labeling of nonmethanotroph microorganisms. Conversely, microcosms supplemented with mineral salts medium exhibited rapid consumption of 13CH4, resulting in the labeling of a less diverse population of only type I methanotrophs. DNA-SIP incubations using water-amended microcosms yielded faster incorporation of 13C into active methanotrophs while avoiding the cross-feeding of 13C. (+info)
A novel lineage of proteobacteria involved in formation of marine Fe-oxidizing microbial mat communities.
(7/23)
BACKGROUND: For decades it has been recognized that neutrophilic Fe-oxidizing bacteria (FeOB) are associated with hydrothermal venting of Fe(II)-rich fluids associated with seamounts in the world's oceans. The evidence was based almost entirely on the mineralogical remains of the microbes, which themselves had neither been brought into culture or been assigned to a specific phylogenetic clade. We have used both cultivation and cultivation-independent techniques to study Fe-rich microbial mats associated with hydrothermal venting at Loihi Seamount, a submarine volcano. METHODOLOGY/PRINCIPLE FINDINGS: Using gradient enrichment techniques, two iron-oxidizing bacteria, strains PV-1 and JV-1, were isolated. Chemolithotrophic growth was observed under microaerobic conditions; Fe(II) and Fe(0) were the only energy sources that supported growth. Both strains produced filamentous stalk-like structures composed of multiple nanometer sized fibrils of Fe-oxyhydroxide. These were consistent with mineralogical structures found in the iron mats. Phylogenetic analysis of the small subunit (SSU) rRNA gene demonstrated that strains PV-1 and JV-1 were identical and formed a monophyletic group deeply rooted within the Proteobacteria. The most similar sequence (85.3% similarity) from a cultivated isolate came from Methylophaga marina. Phylogenetic analysis of the RecA and GyrB protein sequences confirmed that these strains are distantly related to other members of the Proteobacteria. A cultivation-independent analysis of the SSU rRNA gene by terminal-restriction fragment (T-RF) profiling showed that this phylotype was most common in a variety of microbial mats collected at different times and locations at Loihi. CONCLUSIONS: On the basis of phylogenetic and physiological data, it is proposed that isolate PV-1(T) ( = ATCC BAA-1019: JCM 14766) represents the type strain of a novel species in a new genus, Mariprofundus ferrooxydans gen. nov., sp. nov. Furthermore, the strain is the first cultured representative of a new candidatus class of the Proteobacteria that is widely distributed in deep-sea environments, Candidatus zeta (zeta)-Proteobacteria cl. nov. (+info)
Roseomonas terrae sp. nov.
(8/23)
A Gram-negative, non-motile, coccobacilli-shaped bacterium, DS-48T, was isolated from soil from Dokdo, Korea, and its taxonomic position was investigated by means of a polyphasic study. Strain DS-48T grew optimally at 25 degrees C and pH 7.0-8.0 in the presence of 0.5% (w/v) NaCl. It contained Q-10 as the predominant ubiquinone and C18:1omega7c and C18:1 2-OH as the major fatty acids. The DNA G+C content was 69.3 mol%. A phylogenetic analysis based on 16S rRNA gene sequences showed that strain DS-48T fell within the genus Roseomonas, clustering with Roseomonas lacus TH-G33T (at a bootstrap confidence level of 100%). The levels of similarity between the 16S rRNA gene sequence of strain DS-48T and those of the type strains of recognized Roseomonas species were in the range 93.2-98.0%. DNA-DNA relatedness data and differential phenotypic properties, together with the phylogenetic distinctiveness of DS-48T, revealed that this strain differs from recognized Roseomonas species. On the basis of phenotypic, phylogenetic and genetic data, therefore, strain DS-48T represents a novel species within the genus Roseomonas, for which the name Roseomonas terrae sp. nov. is proposed. The type strain is DS-48T (=KCTC 12874T=JCM 14592T). (+info)