RESUMO
Several studies have shown that microbial communities in Antarctic environments are highly diverse. However, considering that the Antarctic Peninsula is among the regions with the fastest warming rates, and that regional climate change has been linked to an increase in the mean rate of glacier retreat, the microbial diversity in Antarctic soil is still poorly understood. In this study, we analysed more than 40 000 sequences of the V5-V6 hypervariable region of the 16S rRNA gene obtained by 454 pyrosequencing from four soil samples from the Wanda Glacier forefield, King George Island, Antarctic Peninsula. Phylotype diversity and richness were surprisingly high, and taxonomic assignment of sequences revealed that communities are dominated by Proteobacteria, Bacteroidetes and Euryarchaeota, with a high frequency of archaeal and bacterial phylotypes unclassified at the genus level and without cultured representative strains, representing a distinct microbial community signature. Several phylotypes were related to marine microorganisms, indicating the importance of the marine environment as a source of colonizers for this recently deglaciated environment. Finally, dominant phylotypes were related to different microorganisms possessing a large array of metabolic strategies, indicating that early successional communities in Antarctic glacier forefield can be also functionally diverse.
Assuntos
Archaea/genética , Bactérias/genética , Camada de Gelo/microbiologia , Consórcios Microbianos/genética , Microbiologia do Solo , Regiões Antárticas , Sequência de Bases , Biodiversidade , Mudança Climática , Meio Ambiente , Proteobactérias/genética , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , SoloRESUMO
Microbial explorations of hot springs have led to remarkable discoveries and improved our understanding of life under extreme conditions. The Andean Mountains harbor diverse habitats, including an extensive chain of geothermal heated water sources. In this study, we describe and compare the planktonic microbial communities present in five high-mountain hot springs with distinct geochemical characteristics, at varying altitudes and geographical locations in the Colombian Andes. The diversity and structure of the microbial communities were assessed by pyrosequencing the V5 - V6 region of the 16S rRNA gene. The planktonic communities varied in terms of diversity indexes and were dominated by the bacterial phyla Proteobacteria, Aquificae, Chloroflexi, Cyanobacteria, Firmicutes, Nitrospirae, and Thermotogae, with site-specific bacterial taxa also observed in some cases. Statistical analyses showed that these microbial communities were distinct from one another and that they clustered in a manner consistent with physicochemical parameters of the environment sampled. Multivariate analysis suggested that pH and sulfate were among the main variables influencing population structure and diversity. The results show that despite their geographical proximity and some shared geochemical characteristics, there were few shared operational taxonomic units (OTUs) and that community structure was influenced mainly by environmental factors that have resulted in different microbial populations.
Assuntos
Fontes Termais/microbiologia , Microbiologia da Água , Altitude , Chloroflexi/genética , Análise por Conglomerados , Colômbia , Cianobactérias/genética , Ecossistema , Euryarchaeota/genética , Genes Arqueais , Genes Bacterianos , Bactérias Gram-Negativas/genética , Fontes Termais/química , Concentração de Íons de Hidrogênio , Tipagem Molecular , Fitoplâncton/genética , Proteobactérias/genética , RNA Ribossômico 16S/genética , Sulfatos/químicaRESUMO
A taxonomic and annotated functional description of microbial life was deduced from 53 Mb of metagenomic sequence retrieved from a planktonic fraction of the Neotropical high Andean (3,973 meters above sea level) acidic hot spring El Coquito (EC). A classification of unassembled metagenomic reads using different databases showed a high proportion of Gammaproteobacteria and Alphaproteobacteria (in total read affiliation), and through taxonomic affiliation of 16S rRNA gene fragments we observed the presence of Proteobacteria, micro-algae chloroplast and Firmicutes. Reads mapped against the genomes Acidiphilium cryptum JF-5, Legionella pneumophila str. Corby and Acidithiobacillus caldus revealed the presence of transposase-like sequences, potentially involved in horizontal gene transfer. Functional annotation and hierarchical comparison with different datasets obtained by pyrosequencing in different ecosystems showed that the microbial community also contained extensive DNA repair systems, possibly to cope with ultraviolet radiation at such high altitudes. Analysis of genes involved in the nitrogen cycle indicated the presence of dissimilatory nitrate reduction to N2 (narGHI, nirS, norBCDQ and nosZ), associated with Proteobacteria-like sequences. Genes involved in the sulfur cycle (cysDN, cysNC and aprA) indicated adenylsulfate and sulfite production that were affiliated to several bacterial species. In summary, metagenomic sequence data provided insight regarding the structure and possible functions of this hot spring microbial community, describing some groups potentially involved in the nitrogen and sulfur cycling in this environment.
Assuntos
Bactérias/classificação , Fontes Termais/microbiologia , Metagenoma , Plâncton/classificação , Bactérias/genética , Cloroplastos/genética , Ecossistema , Transferência Genética Horizontal , Microalgas/genética , Nitrogênio , Plâncton/genética , RNA Ribossômico 16S/genética , Análise de Sequência de DNA/métodos , EnxofreRESUMO
The microbial community of a Colombian high mountain hot spring, El Coquito, was analyzed using three different culture-independent assessments of 16S ribosomal RNA genes: clone libraries, pyrosequencing of the V5-V6 hypervariable region, and microarray. This acidic spring had a diverse community composed mainly of Bacteria that shared characteristics with those from other hot springs and extreme acidic environments. The microbial community was dominated by Proteobacteria, Firmicutes, and Planctomycetes and contained chemotrophic bacteria potentially involved in cycling of ferrous and sulfur-containing minerals and phototrophic organisms, most of which were eukaryotic micro-algae. Despite the presence of a large proportion of novel, unclassified sequences, the taxonomic profiles obtained with each strategy showed similarities at higher taxonomic levels. However, some groups, such as Spirochaetes and Aquificae, were identified using only one methodology, and more taxa were detected with the gene array, which also shared more groups with the pyrosequencing data. Overall, the combined use of different approaches provided a broader view of the microbial community in this acidic hot spring.
Assuntos
Archaea/classificação , Bactérias/classificação , Fontes Termais/microbiologia , Consórcios Microbianos , Actinobacteria/genética , Actinobacteria/isolamento & purificação , Archaea/genética , Archaea/isolamento & purificação , Bactérias/genética , Bactérias/isolamento & purificação , Técnicas de Tipagem Bacteriana , Colômbia , DNA Bacteriano/genética , DNA Ribossômico/genética , Genes de RNAr , Dados de Sequência Molecular , Filogenia , Proteobactérias/genética , Proteobactérias/isolamento & purificação , RNA Ribossômico 16S/genética , Análise de Sequência de DNARESUMO
Identificación de Norovirus Humano (HNoV) en muestras de estiércol de cerdos domésticos. Objetivo: determinar la presencia de NoVs como posible agente zoonótico causal de diarrea aguda entre cerdos y humanos. Materiales y métodos: se recolectaron un total de 77 muestras diarreicas provenientes de niños menores de cinco años y de cerdos menores de dos meses de la población La Chamba en el Tolima, Colombia. Estas muestras fueron transportadas al Laboratorio de Virología de la Pontificia Universidad Javeriana en Bogotá, donde inicialmente se les realizó extracción con Trizol-reagent, siguiendo las instrucciones del fabricante. Una vez obtenido el RNA, el siguiente paso fue hacer la RT-PCR para obtener el producto de amplificacion esperado para NoVs de 213 pb. Finalmente, las muestras positivas obtenidas en la RT-PCR fueron secuenciadas y analizadas mediante métodos bioinformáticos. Resultados: se obtuvieron seis muestras positivas de diarrea de niños y una muestra positiva de diarrea de cerdos, las cuales se evidenciaron en una banda de 231 pb. Cinco de las seis muestras positivas en niños y la muestra positiva en cerdos fueron secuenciadas y analizadas. Conclusiones: dada la estrecha relación genética que se evidencia entre las secuencias del cerdo y el humano, este podría ser un indicio de que exista la posibilidad de un animal en común como reservorio para cepas de humano u otras cepas de animales...
Objective. To determine the presence of NoVs as a possible causal zoonotic agent of acute diarrhea in pigs and humans. Materials and methods. We collected a total of 77 samples from diarrheal children under 5 years and pigs under 2 months from La Chamba town in Tolima, Colombia. These samples were transported to the Laboratory of Virology of the Pontificia Universidad Javeriana in Bogotá, and extraction with Trizol-reagent was done following the manufacturers instructions. After obtaining the RNA, the next step was to perform RT-PCR for obtaining the expected amplification product of 213- bp NoVs. Finally, the positive samples obtained in the RT-PCR were sequenced and analyzed by bioinformatics methods. Results. Six positive diarrheic samples from children and a positive diarrheic sample from pigs were detected by a band of 231 bp. Five of the six positive samples in children and the positive pig sample were sequenced and analyzed. Conclusion. Given the close genetic relationship between pig and human sequences, this could be an indication of the potential existence of a common animal acting as a reservoir for human or other animal strains...
Identificação de Norovírus Humano (HNoV) em amostras de suínos domésticos. Objetivo. Determinar a presença de NoVs como possível agente zoonótico causal de diarréia aguda entre porcos e seres humanos. Materiais e métodos. Foram coletadas um total de 77 amostras de crianças diarréicas menores de cinco anos e porcos com menos de dois meses da população La Chamba Tolima-Colômbia. Estas amostras foram transportadas ao laboratório de virologia da Pontifícia Universidade Javeriana - Bogotá, onde foram inicialmente submetidas à extração com Trizol reagment e seguindo as instruções do fabricante, após a obtenção do RNA o próximo passo foi realizar a RT-PCR para obter o produto de amplificação esperado para NoVs de 213 bp. Finalmente as amostras positivas obtidas no RT-PCR foram seqüenciadas e analisadas por métodos de bioinformática. Resultados. Foram obtidas seis amostras positivas de diarréia nas crianças e uma amostra positiva de diarréia em suínos, as que foram representadas em uma banda de 231 pb. Cinco das seis amostras positivas em crianças e a amostra positiva em suínos foram seqüenciadas e analisadas. Conclusões. Dada a estreita relação genética que se manifesta entre as seqüências de suínos e humanos, isso poderia ser uma indicação de que existe a possibilidade de um animal comum como reservatório para o humano ou outras cepas de animais...
