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BACKGROUND: Frailty is linked to poor outcomes in older patients. We prospectively compared the utility of the picture-based Clinical Frailty Scale (CFS9), clinical assessments, and ultrasound muscle measurements against the reference FRAIL scale in older adult trauma patients in the emergency department (ED). METHODS: We recruited a convenience sample of adults 65â¯yrs. or older with blunt trauma and injury severity scores <9. We queried subjects (or surrogates) on the FRAIL scale, and compared this to: physician-based and subject/surrogate-based CFS9; mid-upper arm circumference (MUAC) and grip strength; and ultrasound (US) measures of muscle thickness (limbs and abdominal wall). We derived optimal diagnostic thresholds and calculated performance metrics for each comparison using sensitivity, specificity, predictive values, and area under receiver operating characteristic curves (AUROC). RESULTS: Fifteen of 65 patients were frail by FRAIL scale (23%). CFS9 performed well when assessed by subject/surrogate (AUROC 0.91 [95% CI 0.84-0.98] or physician (AUROC 0.77 [95% CI 0.63-0.91]. Optimal thresholds for both physician and subject/surrogate were CFS9 of 4 or greater. If both physician and subject/surrogate provided scores <4, sensitivity and negative predictive value were 90.0% (54.1-99.5%) and 95.0% (73.1-99.7%). Grip strength and MUAC were not predictors. US measures that combined biceps and quadriceps thickness showed an AUROC of 0.75 compared to the reference standard. CONCLUSION: The ED needs rapid, validated tools to screen for frailty. The CFS9 has excellent negative predictive value in ruling out frailty. Ultrasound of combined biceps and quadriceps has modest concordance as an alternative in trauma patients who cannot provide a history.
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Serviço Hospitalar de Emergência , Fragilidade/diagnóstico , Avaliação Geriátrica/métodos , Atrofia Muscular/diagnóstico por imagem , Sistemas Automatizados de Assistência Junto ao Leito , Ultrassonografia , Ferimentos não Penetrantes/fisiopatologia , Idoso , Área Sob a Curva , Feminino , Fragilidade/mortalidade , Fragilidade/fisiopatologia , Indicadores Básicos de Saúde , Humanos , Escala de Gravidade do Ferimento , Masculino , Atrofia Muscular/fisiopatologia , Valor Preditivo dos Testes , Estudos ProspectivosRESUMO
The factors driving ß-diversity (variation in community composition) yield insights into the maintenance of biodiversity on the planet. Here we tested whether the mechanisms that underlie bacterial ß-diversity vary over centimeters to continental spatial scales by comparing the composition of ammonia-oxidizing bacteria communities in salt marsh sediments. As observed in studies of macroorganisms, the drivers of salt marsh bacterial ß-diversity depend on spatial scale. In contrast to macroorganism studies, however, we found no evidence of evolutionary diversification of ammonia-oxidizing bacteria taxa at the continental scale, despite an overall relationship between geographic distance and community similarity. Our data are consistent with the idea that dispersal limitation at local scales can contribute to ß-diversity, even though the 16S rRNA genes of the relatively common taxa are globally distributed. These results highlight the importance of considering multiple spatial scales for understanding microbial biogeography.
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Bactérias/genética , Bactérias/metabolismo , Biodiversidade , Amônia/metabolismo , Bactérias/classificação , Betaproteobacteria/classificação , Betaproteobacteria/genética , Betaproteobacteria/metabolismo , Ecossistema , Genes Bacterianos , Dados de Sequência Molecular , Filogenia , RNA Bacteriano/genética , RNA Ribossômico 16S/genéticaRESUMO
BACKGROUND: Actinobacteria represent a consistent component of most marine bacterial communities yet little is known about the mechanisms by which these Gram-positive bacteria adapt to life in the marine environment. Here we employed a phylogenomic approach to identify marine adaptation genes in marine Actinobacteria. The focus was on the obligate marine actinomycete genus Salinispora and the identification of marine adaptation genes that have been acquired from other marine bacteria. RESULTS: Functional annotation, comparative genomics, and evidence of a shared evolutionary history with bacteria from hyperosmotic environments were used to identify a pool of more than 50 marine adaptation genes. An Actinobacterial species tree was used to infer the likelihood of gene gain or loss in accounting for the distribution of each gene. Acquired marine adaptation genes were associated with electron transport, sodium and ABC transporters, and channels and pores. In addition, the loss of a mechanosensitive channel gene appears to have played a major role in the inability of Salinispora strains to grow following transfer to low osmotic strength media. CONCLUSIONS: The marine Actinobacteria for which genome sequences are available are broadly distributed throughout the Actinobacterial phylogenetic tree and closely related to non-marine forms suggesting they have been independently introduced relatively recently into the marine environment. It appears that the acquisition of transporters in Salinispora spp. represents a major marine adaptation while gene loss is proposed to play a role in the inability of this genus to survive outside of the marine environment. This study reveals fundamental differences between marine adaptations in Gram-positive and Gram-negative bacteria and no common genetic basis for marine adaptation among the Actinobacteria analyzed.
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Adaptação Fisiológica/genética , Genoma Bacteriano , Genômica , Micromonosporaceae/genética , Actinobacteria/classificação , Actinobacteria/genética , Transporte Biológico/genética , Ordem dos Genes , Genes Bacterianos , Micromonosporaceae/classificação , Óperon , Fosfatos/metabolismo , Filogenia , Água do Mar/microbiologiaRESUMO
The subsurface microbiology of an Athabasca oil sands reservoir in western Canada containing severely biodegraded oil was investigated by combining 16S rRNA gene- and polar lipid-based analyses of reservoir formation water with geochemical analyses of the crude oil and formation water. Biomass was filtered from formation water, DNA was extracted using two different methods, and 16S rRNA gene fragments were amplified with several different primer pairs prior to cloning and sequencing or community fingerprinting by denaturing gradient gel electrophoresis (DGGE). Similar results were obtained irrespective of the DNA extraction method or primers used. Archaeal libraries were dominated by Methanomicrobiales (410 of 414 total sequences formed a dominant phylotype affiliated with a Methanoregula sp.), consistent with the proposed dominant role of CO(2) -reducing methanogens in crude oil biodegradation. In two bacterial 16S rRNA clone libraries generated with different primer pairs, > 99% and 100% of the sequences were affiliated with Epsilonproteobacteria (n = 382 and 72 total clones respectively). This massive dominance of Epsilonproteobacteria sequences was again obtained in a third library (99% of sequences; n = 96 clones) using a third universal bacterial primer pair (inosine-341f and 1492r). Sequencing of bands from DGGE profiles and intact polar lipid analyses were in accordance with the bacterial clone library results. Epsilonproteobacterial OTUs were affiliated with Sulfuricurvum, Arcobacter and Sulfurospirillum spp. detected in other oil field habitats. The dominant organism revealed by the bacterial libraries (87% of all sequences) is a close relative of Sulfuricurvum kujiense - an organism capable of oxidizing reduced sulfur compounds in crude oil. Geochemical analysis of organic extracts from bitumen at different reservoir depths down to the oil water transition zone of these oil sands indicated active biodegradation of dibenzothiophenes, and stable sulfur isotope ratios for elemental sulfur and sulfate in formation waters were indicative of anaerobic oxidation of sulfur compounds. Microbial desulfurization of crude oil may be an important metabolism for Epsilonproteobacteria indigenous to oil reservoirs with elevated sulfur content and may explain their prevalence in formation waters from highly biodegraded petroleum systems.
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Epsilonproteobacteria/crescimento & desenvolvimento , Campos de Petróleo e Gás/microbiologia , Petróleo/metabolismo , Sequência de Bases , Biodegradação Ambiental , Canadá , Epsilonproteobacteria/classificação , Epsilonproteobacteria/genética , Epsilonproteobacteria/metabolismo , Genes de RNAr , Dados de Sequência Molecular , Petróleo/análise , Petróleo/microbiologia , Filogenia , Análise de Sequência de DNA , Enxofre/metabolismo , Microbiologia da ÁguaRESUMO
Marine actinomycetes in the genus Salinispora fail to grow when seawater is replaced with deionized (DI) water in complex growth media. While bioinformatic analyses have led to the identification of a number of candidate marine adaptation genes, there is currently no experimental evidence to support the genetic basis for the osmotic requirements associated with this taxon. One hypothesis is that the lineage-specific loss of mscL is responsible for the failure of strains to grow in media prepared with DI water. The mscL gene encodes a conserved transmembrane protein that reduces turgor pressure under conditions of acute osmotic downshock. In the present study, the mscL gene from a Micromonospora strain capable of growth on media prepared with DI water was transformed into S. tropica strain CNB-440. The single-copy, chromosomal genetic complementation yielded a recombinant Salinispora mscL(+) strain that demonstrated an increased capacity to survive osmotic downshock. The enhanced survival of the S. tropica transformant provides experimental evidence that the loss of mscL is associated with the failure of Salinispora spp. to grow in low-osmotic-strength media.
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Canais Iônicos/metabolismo , Micromonosporaceae/fisiologia , Pressão Osmótica , Estresse Fisiológico , Meios de Cultura/química , Teste de Complementação Genética , Canais Iônicos/genética , Viabilidade Microbiana , Micromonosporaceae/genética , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismoRESUMO
Bacteria of the genus Frankia are mycelium-forming actinomycetes that are found as nitrogen-fixing facultative symbionts of actinorhizal plants. Although soil-dwelling actinomycetes are well-known producers of bioactive compounds, the genus Frankia has largely gone uninvestigated for this potential. Bioinformatic analysis of the genome sequences of Frankia strains ACN14a, CcI3, and EAN1pec revealed an unexpected number of secondary metabolic biosynthesis gene clusters. Our analysis led to the identification of at least 65 biosynthetic gene clusters, the vast majority of which appear to be unique and for which products have not been observed or characterized. More than 25 secondary metabolite structures or structure fragments were predicted, and these are expected to include cyclic peptides, siderophores, pigments, signaling molecules, and specialized lipids. Outside the hopanoid gene locus, no cluster could be convincingly demonstrated to be responsible for the few secondary metabolites previously isolated from other Frankia strains. Few clusters were shared among the three species, demonstrating species-specific biosynthetic diversity. Proteomic analysis of Frankia sp. strains CcI3 and EAN1pec showed that significant and diverse secondary metabolic activity was expressed in laboratory cultures. In addition, several prominent signals in the mass range of peptide natural products were observed in Frankia sp. CcI3 by intact-cell matrix-assisted laser desorption-ionization mass spectrometry (MALDI-MS). This work supports the value of bioinformatic investigation in natural products biosynthesis using genomic information and presents a clear roadmap for natural products discovery in the Frankia genus.
Assuntos
Produtos Biológicos/biossíntese , Vias Biossintéticas/genética , Frankia/genética , Frankia/metabolismo , Genômica , Proteômica , Família MultigênicaRESUMO
Elevated seawater temperatures have contributed to the rise of coral disease mediated by bacterial pathogens, such as the globally distributed Vibrio coralliilyticus, which utilizes coral mucus as a chemical cue to locate stressed corals. However, the physiological events in the pathogens that follow their entry into the coral host environment remain unknown. Here, we present simultaneous measurements of the behavioral and transcriptional responses of V. coralliilyticus BAA-450 incubated in coral mucus. Video microscopy revealed a strong and rapid chemokinetic behavioral response by the pathogen, characterized by a two-fold increase in average swimming speed within 6 min of coral mucus exposure. RNA sequencing showed that this bacterial behavior was accompanied by an equally rapid differential expression of 53% of the genes in the V. coralliilyticus genome. Specifically, transcript abundance 10 min after mucus exposure showed upregulation of genes involved in quorum sensing, biofilm formation, and nutrient metabolism, and downregulation of flagella synthesis and chemotaxis genes. After 60 min, we observed upregulation of genes associated with virulence, including zinc metalloproteases responsible for causing coral tissue damage and algal symbiont photoinactivation, and secretion systems that may export toxins. Together, our results suggest that V. coralliilyticus employs a suite of behavioral and transcriptional responses to rapidly shift into a distinct infection mode within minutes of exposure to the coral microenvironment.
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Antozoários , Vibrio , Animais , Quimiotaxia , Muco , Água do Mar , Vibrio/genética , VirulênciaRESUMO
The complete genomes of three strains from the phylum Acidobacteria were compared. Phylogenetic analysis placed them as a unique phylum. They share genomic traits with members of the Proteobacteria, the Cyanobacteria, and the Fungi. The three strains appear to be versatile heterotrophs. Genomic and culture traits indicate the use of carbon sources that span simple sugars to more complex substrates such as hemicellulose, cellulose, and chitin. The genomes encode low-specificity major facilitator superfamily transporters and high-affinity ABC transporters for sugars, suggesting that they are best suited to low-nutrient conditions. They appear capable of nitrate and nitrite reduction but not N(2) fixation or denitrification. The genomes contained numerous genes that encode siderophore receptors, but no evidence of siderophore production was found, suggesting that they may obtain iron via interaction with other microorganisms. The presence of cellulose synthesis genes and a large class of novel high-molecular-weight excreted proteins suggests potential traits for desiccation resistance, biofilm formation, and/or contribution to soil structure. Polyketide synthase and macrolide glycosylation genes suggest the production of novel antimicrobial compounds. Genes that encode a variety of novel proteins were also identified. The abundance of acidobacteria in soils worldwide and the breadth of potential carbon use by the sequenced strains suggest significant and previously unrecognized contributions to the terrestrial carbon cycle. Combining our genomic evidence with available culture traits, we postulate that cells of these isolates are long-lived, divide slowly, exhibit slow metabolic rates under low-nutrient conditions, and are well equipped to tolerate fluctuations in soil hydration.
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Bactérias/genética , Bactérias/isolamento & purificação , DNA Bacteriano/genética , Genoma Bacteriano , Microbiologia do Solo , Antibacterianos/biossíntese , Transporte Biológico , Metabolismo dos Carboidratos , Cianobactérias/genética , DNA Bacteriano/química , Fungos/genética , Macrolídeos/metabolismo , Dados de Sequência Molecular , Nitrogênio/metabolismo , Filogenia , Proteobactérias/genética , Análise de Sequência de DNA , Homologia de SequênciaRESUMO
The fish fauna of the Southern Ocean is dominated by species of the perciform suborder Notothenioidei, which constitute 46% of fish species and 90% of biomass. Notothenioids have undergone rapid morphological and ecological diversification and developed physiological adaptations to a cold, highly oxygenated environment. Microbes inhabiting animal intestines include those that perform essential nutritional functions, but notothenioid gut microbial communities have not been investigated using cultivation-independent approaches. We analyzed bacterial 16S rRNA gene sequences obtained from the intestinal tract of Notothenia coriiceps and Chaenocephalus aceratus, which differ in their pelagic distribution and feeding strategies. Both samples showed dominance of Gammaproteobacteria (mostly Vibrionaceae), as has been reported for temperate teleost species. Both samples showed low diversity relative to that reported for other fish microbiota studies, with C. aceratus containing fewer OTUs than N. coriiceps. Despite the small sample size of this preliminary study, our findings suggest that Antarctic notothenioids carry a gut microbiota similar in composition to that of temperate fish, but exhibiting lower species-level diversity. The omnivorous N. coriiceps individual exhibited greater diversity than the exclusively carnivorous C. aceratus individual, which may indicate that increasing herbivory in fish leads to gut microbe diversification, as found in mammals. Lastly, we detected members of taxa containing known microbial pathogens, which have not been previously reported in Antarctic notothenioid fish.
Assuntos
Intestinos/microbiologia , Perciformes/microbiologia , Algoritmos , Animais , Regiões Antárticas , Biodiversidade , Biomassa , Biblioteca Gênica , Variação Genética , Filogenia , RNA Ribossômico 16S/metabolismo , Software , Especificidade da EspécieRESUMO
Importance: Older adults are disproportionately affected by trauma and accounted for 47% of trauma fatalities in 2016. In many populations and disease processes, described risk factors for poor clinical outcomes include sarcopenia and brain atrophy, but these remain to be fully characterized in older trauma patients. Sarcopenia and brain atrophy may be opportunistically evaluated via head computed tomography, which is often performed during the initial trauma evaluation. Objective: To investigate the association of masseter sarcopenia and brain atrophy with 1-year mortality among trauma patients older than 65 years by using opportunistic computed tomography imaging. Design, Setting, and Participants: This retrospective cohort study was conducted in a level 1 trauma center from January 1, 2011, to December 31, 2014, with a 1-year follow-up to assess mortality. Washington state residents 65 years or older who were admitted to the trauma intensive care unit with a head Abbreviated Injury Scale score of less than 3 were eligible. Patients with incomplete data and death within 1 day of admission were excluded. Data analysis was completed from June 2017 to October 2018. Exposures: Masseter muscle cross-sectional area and brain atrophy index were measured using a standard clinical Picture Archiving and Communication System application to assess for sarcopenia and brain atrophy, respectively. Main Outcomes and Measures: Primary outcome was 1-year mortality. Secondary outcomes were discharge disposition and 30-day mortality. Results: The study cohort included 327 patients; 72 (22.0%) had sarcopenia only, 71 (21.7%) had brain atrophy only, 92 (28.1%) had both, and 92 (28.1%) had neither. The mean (SD) age was 77.8 (8.6) years, and 159 patients (48.6%) were women. After adjustment for age, comorbidity, complications, and injury characteristics, masseter sarcopenia and brain atrophy were both independently and cumulatively associated with mortality (masseter muscle cross-sectional area per SD less than the mean: hazard ratio, 2.0 [95% CI, 1.2-3.1]; P = .005; brain atrophy index per SD greater than the mean: hazard ratio, 2.0 [95% CI, 1.1-3.5]; P = .02). Conclusions and Relevance: Masseter muscle sarcopenia and brain atrophy were independently and cumulatively associated with 1-year mortality in older trauma patients after adjustment for other clinical factors. These radiologic indicators are easily measured opportunistically through standard imaging software. The results can potentially guide conversations regarding prognosis and interventions with patients and their families.
Assuntos
Lesões Encefálicas/complicações , Encéfalo/diagnóstico por imagem , Músculo Masseter/diagnóstico por imagem , Sarcopenia/etiologia , Tomografia Computadorizada por Raios X/métodos , Idoso , Idoso de 80 Anos ou mais , Atrofia/complicações , Atrofia/diagnóstico , Atrofia/metabolismo , Lesões Encefálicas/diagnóstico , Lesões Encefálicas/mortalidade , Feminino , Seguimentos , Humanos , Masculino , Prognóstico , Estudos Retrospectivos , Fatores de Risco , Sarcopenia/diagnóstico , Sarcopenia/mortalidade , Taxa de Sobrevida/tendências , Fatores de Tempo , Washington/epidemiologiaRESUMO
Supercritical carbon dioxide (scCO2) is an attractive substitute for conventional organic solvents due to its unique transport and thermodynamic properties, its renewability and labile nature, and its high solubility for compounds such as alcohols, ketones, and aldehydes. However, biological systems that use scCO2 are mainly limited to in vitro processes due to its strong inhibition of cell viability and growth. To solve this problem, we used a bioprospecting approach to isolate a microbial strain with the natural ability to grow while exposed to scCO2. Enrichment culture and serial passaging of deep subsurface fluids from the McElmo Dome scCO2 reservoir in aqueous media under scCO2 headspace enabled the isolation of spore-forming strain Bacillus megaterium SR7. Sequencing and analysis of the complete 5.51 Mbp genome and physiological characterization revealed the capacity for facultative anaerobic metabolism, including fermentative growth on a diverse range of organic substrates. Supplementation of growth medium with L-alanine for chemical induction of spore germination significantly improved growth frequencies and biomass accumulation under scCO2 headspace. Detection of endogenous fermentative compounds in cultures grown under scCO2 represents the first observation of bioproduct generation and accumulation under this condition. Culturing development and metabolic characterization of B. megaterium SR7 represent initial advancements in the effort toward enabling exploitation of scCO2 as a sustainable solvent for in vivo bioprocessing.
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Over recent decades several coral diseases have been reported as a significant threat to coral reef ecosystems causing the decline of corals cover and diversity around the world. The development of techniques that improve the ability to detect and quantify microbial agents involved in coral disease will aid in the elucidation of disease cause, facilitating coral disease detection and diagnosis, identification and pathogen monitoring, pathogen sources, vectors, and reservoirs. The genus Vibrio is known to harbor pathogenic strains to marine organisms. One of the best-characterized coral pathogens is Vibrio coralliilyticus, an aetilogic agent of White Plague Disease (WPD). We used Mussismilia coral tissue (healthy and diseased specimens) to develop a rapid reproducible detection system for vibrios based on RT-QPCR and SYBR chemistry. We were able to detect total vibrios in expressed RNA targeting the 16S rRNA gene at 5.23 × 106 copies/µg RNA and V. coralliilyticus targeting the pyrH gene at 5.10 × 103 copies/µg RNA in coral tissue. Detection of V. coralliilyticus in diseased and in healthy samples suggests that WPD in the Abrolhos Bank may be caused by a consortium of microorganism and not only a single pathogen. We developed a more practical and economic system compared with probe uses for the real-time detection and quantification of vibrios from coral tissues by using the 16S rRNA and pyrH gene. This qPCR assay is a reliable tool for the monitoring of coral pathogens, and can be useful to prevent, control, or reduce impacts in this ecosystem.
Assuntos
Evolução Molecular , Genoma Bacteriano/genética , Genômica/métodos , Lactamas/metabolismo , Micromonosporaceae/genética , Micromonosporaceae/metabolismo , Sequência de Aminoácidos , Vias Biossintéticas , Modelos Moleculares , Conformação Molecular , Dados de Sequência Molecular , Peptídeo Sintases/química , Peptídeo Sintases/genética , Peptídeo Sintases/metabolismo , FilogeniaRESUMO
We have characterized the molecular and genomic diversity of the microbiota of the starlet sea anemone Nematostella vectensis, a cnidarian model for comparative developmental and functional biology and a year-round inhabitant of temperate salt marshes. Molecular phylogenetic analysis of 16S rRNA gene clone libraries revealed four ribotypes associated with N. vectensis at multiple locations and times. These associates include two novel ribotypes within the ε-Proteobacterial order Campylobacterales and the Spirochetes, respectively, each sharing <85% identity with cultivated strains, and two γ-Proteobacterial ribotypes sharing >99% 16S rRNA identity with Endozoicomonas elysicola and Pseudomonas oleovorans, respectively. Species-specific PCR revealed that these populations persisted in N. vectensis asexually propagated under laboratory conditions. cDNA indicated expression of the Campylobacterales and Endozoicomonas 16S rRNA in anemones from Sippewissett Marsh, MA. A collection of bacteria from laboratory raised N. vectensis was dominated by isolates from P. oleovorans and Rhizobium radiobacter. Isolates from field-collected anemones revealed an association with Limnobacter and Stappia isolates. Genomic DNA sequencing was carried out on 10 cultured bacterial isolates representing field- and laboratory-associates, i.e., Limnobacter spp., Stappia spp., P. oleovorans and R. radiobacter. Genomes contained multiple genes identified as virulence (host-association) factors while S. stellulata and L. thiooxidans genomes revealed pathways for mixotrophic sulfur oxidation. A pilot metatranscriptome of laboratory-raised N. vectensis was compared to the isolate genomes and indicated expression of ORFs from L. thiooxidans with predicted functions of motility, nutrient scavenging (Fe and P), polyhydroxyalkanoate synthesis for carbon storage, and selective permeability (porins). We hypothesize that such activities may mediate acclimation and persistence of bacteria in a N. vectensis holobiont defined by both internal and external gradients of chemicals and nutrients in a dynamic coastal habitat.
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Cyanobacterial harmful algal blooms (cyanoHABs) appear to be increasing in frequency on a global scale. The Cyanobacteria in blooms can produce toxic secondary metabolites that make freshwater dangerous for drinking and recreation. To characterize microbial activities in a cyanoHAB, transcripts from a eutrophic freshwater reservoir in Singapore were sequenced for six samples collected over one day-night period. Transcripts from the Cyanobacterium Microcystis dominated all samples and were accompanied by at least 533 genera primarily from the Cyanobacteria, Proteobacteria, Bacteroidetes and Actinobacteria. Within the Microcystis population, abundant transcripts were from genes for buoyancy, photosynthesis and synthesis of the toxin microviridin, suggesting that these are necessary for competitive dominance in the Reservoir. During the day, Microcystis transcripts were enriched in photosynthesis and energy metabolism while at night enriched pathways included DNA replication and repair and toxin biosynthesis. Microcystis was the dominant source of transcripts from polyketide and non-ribosomal peptide synthase (PKS and NRPS, respectively) gene clusters. Unexpectedly, expression of all PKS/NRPS gene clusters, including for the toxins microcystin and aeruginosin, occurred throughout the day-night cycle. The most highly expressed PKS/NRPS gene cluster from Microcystis is not associated with any known product. The four most abundant phyla in the reservoir were enriched in different functions, including photosynthesis (Cyanobacteria), breakdown of complex organic molecules (Proteobacteria), glycan metabolism (Bacteroidetes) and breakdown of plant carbohydrates, such as cellobiose (Actinobacteria). These results provide the first estimate of secondary metabolite gene expression, functional partitioning and functional interplay in a freshwater cyanoHAB.
Assuntos
Cianobactérias/genética , Água Doce/microbiologia , Proliferação Nociva de Algas , Microcystis/genética , Bactérias/classificação , Bactérias/genética , Bactérias/metabolismo , Cianobactérias/metabolismo , Expressão Gênica , Proteínas de Membrana Transportadoras/genética , Proteínas de Membrana Transportadoras/metabolismo , Microcystis/metabolismo , Plâncton/classificação , Plâncton/genética , Plâncton/metabolismo , Metabolismo SecundárioRESUMO
New bioinformatic tools are needed to analyze the growing volume of DNA sequence data. This is especially true in the case of secondary metabolite biosynthesis, where the highly repetitive nature of the associated genes creates major challenges for accurate sequence assembly and analysis. Here we introduce the web tool Natural Product Domain Seeker (NaPDoS), which provides an automated method to assess the secondary metabolite biosynthetic gene diversity and novelty of strains or environments. NaPDoS analyses are based on the phylogenetic relationships of sequence tags derived from polyketide synthase (PKS) and non-ribosomal peptide synthetase (NRPS) genes, respectively. The sequence tags correspond to PKS-derived ketosynthase domains and NRPS-derived condensation domains and are compared to an internal database of experimentally characterized biosynthetic genes. NaPDoS provides a rapid mechanism to extract and classify ketosynthase and condensation domains from PCR products, genomes, and metagenomic datasets. Close database matches provide a mechanism to infer the generalized structures of secondary metabolites while new phylogenetic lineages provide targets for the discovery of new enzyme architectures or mechanisms of secondary metabolite assembly. Here we outline the main features of NaPDoS and test it on four draft genome sequences and two metagenomic datasets. The results provide a rapid method to assess secondary metabolite biosynthetic gene diversity and richness in organisms or environments and a mechanism to identify genes that may be associated with uncharacterized biochemistry.
Assuntos
Biologia Computacional/métodos , Computadores , Variação Genética , Genoma , Internet , Funções Verossimilhança , Cadeias de Markov , Biossíntese de Peptídeos Independentes de Ácido Nucleico , Peptídeo Sintases/genética , Peptídeo Sintases/metabolismo , Filogenia , Policetídeo Sintases/genética , Policetídeo Sintases/metabolismo , Estrutura Terciária de Proteína , Análise de Sequência de DNA , Microbiologia do Solo , Streptomyces/metabolismoRESUMO
Genomic islands have been shown to harbor functional traits that differentiate ecologically distinct populations of environmental bacteria. A comparative analysis of the complete genome sequences of the marine Actinobacteria Salinispora tropica and Salinispora arenicola reveals that 75% of the species-specific genes are located in 21 genomic islands. These islands are enriched in genes associated with secondary metabolite biosynthesis providing evidence that secondary metabolism is linked to functional adaptation. Secondary metabolism accounts for 8.8% and 10.9% of the genes in the S. tropica and S. arenicola genomes, respectively, and represents the major functional category of annotated genes that differentiates the two species. Genomic islands harbor all 25 of the species-specific biosynthetic pathways, the majority of which occur in S. arenicola and may contribute to the cosmopolitan distribution of this species. Genome evolution is dominated by gene duplication and acquisition, which in the case of secondary metabolism provide immediate opportunities for the production of new bioactive products. Evidence that secondary metabolic pathways are exchanged horizontally, coupled with earlier evidence for fixation among globally distributed populations, supports a functional role and suggests that the acquisition of natural product biosynthetic gene clusters represents a previously unrecognized force driving bacterial diversification. Species-specific differences observed in clustered regularly interspaced short palindromic repeat sequences suggest that S. arenicola may possess a higher level of phage immunity, whereas a highly duplicated family of polymorphic membrane proteins provides evidence for a new mechanism of marine adaptation in Gram-positive bacteria.
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Actinobacteria/fisiologia , Adaptação Biológica , Adaptação Fisiológica , Ilhas Genômicas , Actinobacteria/genética , Actinobacteria/metabolismo , DNA Bacteriano/química , DNA Bacteriano/genética , Evolução Molecular , Duplicação Gênica , Transferência Genética Horizontal , Genoma Bacteriano , Redes e Vias Metabólicas/genética , Dados de Sequência Molecular , Água do Mar/microbiologia , Análise de Sequência de DNA , SinteniaRESUMO
Although microbes associated with shallow-water corals have been reported, deepwater coral microbes are poorly characterized. A cultivation-independent analysis of Alaskan seamount octocoral microflora showed that Proteobacteria (classes Alphaproteobacteria and Gammaproteobacteria), Firmicutes, Bacteroidetes, and Acidobacteria dominate and vary in abundance. More sampling is needed to understand the basis and significance of this variation.