Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 12 de 12
Filtrar
Mais filtros










Filtros aplicados
Base de dados
Intervalo de ano de publicação
1.
Int. microbiol ; 22(4): 403-409, dic. 2019. graf, tab
Artigo em Inglês | IBECS | ID: ibc-185058

RESUMO

A biofilm is a community of microorganisms attached to a surface and embedded in a matrix of extracellular polymeric substances. Biofilms confer resistance towards conventional antibiotic treatments; thus, there is an urgent need for newer and more effective antimicrobial agents that can act against these biofilms. Due to this situation, various studies have been done to investigate the anti-biofilm effects of natural products including bioactive compounds extracted from microorganisms such as Actinobacteria. This review provides an insight into the anti-biofilm potential of Actinobacteria against various pathogenic bacteria, which hopefully provides useful information, guidance, and improvements for future antimicrobial studies. Nevertheless, further research on the anti-biofilm mechanisms and compound modifications to produce more potent anti-biofilm effects are required


No disponible


Assuntos
Actinobacteria/isolamento & purificação , Streptomyces/fisiologia , Biofilmes/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Actinobacteria/genética , Actinobacteria/efeitos dos fármacos
2.
Int. microbiol ; 22(3): 377-390, sept. 2019. mapas, graf, tab
Artigo em Inglês | IBECS | ID: ibc-184845

RESUMO

Easter Island is an isolated volcanic island in the Pacific Ocean. Despite the extended knowledge about its origin, flora, and fauna, little is known about the bacterial diversity inhabiting this territory. Due to its isolation, Easter Island can be considered as a suitable place to evaluate microbial diversity in a geographically isolated context, what could shed light on actinobacterial occurrence, distribution, and potential novelty. In the present study, we performed a comprehensive analysis of marine Actinobacteria diversity of Easter Island by studying a large number of coastal sampling sites, which were inoculated into a broad spectrum of different culture media, where most important variations in composition included carbon and nitrogen substrates, in addition to salinity. The isolates were characterized on the basis of 16S ribosomal RNA gene sequencing and phylogenetic analysis. High actinobacterial diversity was recovered with a total of 163 pure cultures of Actinobacteria representing 72 phylotypes and 20 genera, which were unevenly distributed in different locations of the island and sample sources. The phylogenetic evaluation indicated a high degree of novelty showing that 45% of the isolates might represent new taxa. The most abundant genera in the different samples were Micromonospora, Streptomyces, Salinispora, and Dietzia. Two aspects appear of primary importance in regard to the high degree of novelty and diversity of Actinobacteria found. First, the application of various culture media significantly increased the number of species and genera obtained. Second, the geographical isolation is considered to be of importance regarding the actinobacterial novelty found


No disponible


Assuntos
Actinobacteria/classificação , Actinobacteria/isolamento & purificação , Biodiversidade , Microbiologia Ambiental , Actinobacteria/genética , Técnicas Bacteriológicas , Chile , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Filogenia , Polinésia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
3.
Int. microbiol ; 22(2): 191-201, jun. 2019. ilus, graf, tab
Artigo em Inglês | IBECS | ID: ibc-184826

RESUMO

In this study, endophytic bacteria isolated from root, stem, and leaf tissues of stripe rust-susceptible (Inqilab 91, Galaxy 2013, and 15BT023) and stripe rust-resistant (NARC 2011, Ujala 2015, TW1410) cultivars were identified and characterized. Abundance of endophytes was found in roots as compared with stems and leaves. Resistant and susceptible cultivars significantly differed in abundance of endophytic bacteria. Restriction analysis of 16S rRNA genes amplified from 100 bacterial isolates produced 17 unique patterns. Representatives of each of the 17 unique patterns were sequenced and identified. Among the sequenced bacteria, 8 belonged to Firmicutes, 7 were Proteobacteria, and 2 were Actinobacteria. Most of the isolates have plant growth-promoting properties and a few have the potential of producing hydrolytic enzymes. Two isolates showed significant inhibition of rust spore germination. These endophytic bacteria not only can be helpful in growth-promoting activities but also can assist in biocontrol of stripe rust disease


No disponible


Assuntos
Endófitos/isolamento & purificação , Raízes de Plantas/microbiologia , Phakopsora pachyrhizi/isolamento & purificação , RNA Ribossômico 16S/isolamento & purificação , Bactérias/isolamento & purificação , RNA Ribossômico 16S/genética , RNA Ribossômico 16S/metabolismo , Firmicutes/isolamento & purificação , Actinobacteria/enzimologia , Actinobacteria/isolamento & purificação , Esporos Bacterianos/crescimento & desenvolvimento , Esporos Fúngicos/isolamento & purificação , Paquistão
6.
Int. microbiol ; 19(1): 15-26, mar. 2016. ilus, graf, tab
Artigo em Inglês | IBECS | ID: ibc-157080

RESUMO

The use of native strains of microorganisms from soils is an excellent option for bioremediation. To our knowledge, until now there has been no other group working on the isolation of Actinobacteria from contaminated soils in Mexico. In this study, samples of soils close to areas with oil activity in the State of Veracruz, Mexico, were inoculated for the isolation of Actinobacteria. The strains isolated were characterized morphologically, and the concentrations of NaCl and pH were determined for optimal growth. Strain selection was performed by the detection of a phylogenetic marker for Actinobacteria located at the 23S rRNA gene, followed by species identification by sequencing the 16S rRNA gene. Several haloalkalitolerant Actinobacteria were isolated and identified as: Kocuria rosea, K. palustris, Microbacterium testaceum, Nocardia farcinica and Cellulomonas denverensis. Except for C. denverensis, the biomass of all strains increased in the presence of anthracene. The strains capacity to metabolize anthracene (at 48 h), determined by fluorescence emission, was in the range of 46-54%. During this time, dihydroxy aromatic compounds formed, characterized by attenuated total reflectance Fourier transform infrared spectroscopy bands of 1205 cm-1 and 1217 cm-1. Those Actinobacteria are potentially useful for the bioremediation of saline and alkaline environments contaminated with polycyclic aromatic hydrocarbon compounds (AU)


No disponible


Assuntos
Actinobacteria/patogenicidade , Antracenos/metabolismo , Poluição Ambiental , Hidrocarbonetos Policíclicos Aromáticos/análise , Microbiologia do Solo , Alcalinidade do Solo/análise , Solos Salitrosos/análise
7.
Int. microbiol ; 19(1): 39-47, mar. 2016. graf
Artigo em Inglês | IBECS | ID: ibc-157083

RESUMO

The National Center for Biotechnology Information [http://www.ncbi.nlm.nih.gov/guide/taxonomy/] database enlists more than 15,500 bacterial species. But this also includes a plethora of uncultured bacterial representations. Owing to their metabolism, they directly influence biogeochemical cycles, which underscores the important status of bacteria on our planet. To study the function of a gene from an uncultured bacterium, we have undertaken a de novo gene synthesis approach. Actinobacteria of the acI-B subcluster are important but yet uncultured members of the bacterioplankton in temperate lakes of the northern hemisphere such as oligotrophic Lake Stechlin (NE Germany). This lake is relatively poor in phosphate (P) and harbors on average ~1.3 x 106 bacterial cells/ml, whereby Actinobacteria of the ac-I lineage can contribute to almost half of the entire bacterial community depending on seasonal variability. Single cell genome analysis of Actinobacterium SCGC AB141-P03, a member of the acI-B tribe in Lake Stechlin has revealed several phosphate-metabolizing genes. The genome of acI-B Actinobacteria indicates potential to degrade polyphosphate compound. To test for this genetic potential, we targeted the exoP-annotated gene potentially encoding polyphosphatase and synthesized it artificially to examine its biochemical role. Heterologous overexpression of the gene in Escherichia coli and protein purification revealed phosphatase activity. Comparative genome analysis suggested that homologs of this gene should be also present in other Actinobacteria of the acI lineages. This strategic retention of specialized genes in their genome provides a metabolic advantage over other members of the aquatic food web in a P-limited ecosystem (AU)


No disponible


Assuntos
Humanos , Actinobacteria/genética , Monoéster Fosfórico Hidrolases/genética , Genoma Bacteriano , Microbiologia da Água , Genes Bacterianos/genética , Filogenia
8.
Rev. esp. enferm. dig ; 107(11): 659-671, nov. 2015. tab, ilus
Artigo em Inglês | IBECS | ID: ibc-145294

RESUMO

Background and aim: The human colonic mucosa is populated by a wide range of microorganisms, usually in a symbiotic relation with the host. Sometimes this balance is lost and a state of dysbiosis arises, exposing the colon to different metabolic and inflammatory stimuli (according to the microbiota’s changing profile). Recent findings lead to hypothesize that this unbalance may create a subclinical pro-inflammatory state that increases DNA mutations and, therefore, colorectal carcinogenesis. In this article we aim to systematically review the scientific evidence regarding colonic microbiota and its role in colorectal carcinogenesis. Methods: Systematic review of PubMed searching results for original articles studying microbiota and colorectal cancer until November 2014. Results: Thirty-one original articles studied the role of colon microbiota in colorectal carcinoma including both human and animal studies. Different and heterogeneous methods were used and different bacteria were considered. Nevertheless, some bacteria are consistently augmented (such as Fusobacteria, Alistipes, Porphyromonadaceae, Coriobacteridae, Staphylococcaceae,Akkermansia spp. and Methanobacteriales), while other are constantly diminished in colorectal cancer (such as Bifidobacterium,Lactobacillus, Ruminococcus, Faecalibacterium spp., Roseburia, and Treponema). Moreover, bacteria metabolites amino acids are increased and butyrate is decreased throughout colonic carcinogenesis. Conclusion: Conclusive evidence shows that colorectal carcinogenesis is associated with microbial dysbiosis. This information may be used to create new prophylactic, diagnostic and therapeutic strategies for colorectal cáncer (AU)


Assuntos
Feminino , Humanos , Masculino , Microbiota/fisiologia , Carcinogênese/patologia , Neoplasias Colorretais/complicações , Neoplasias Colorretais/diagnóstico , Neoplasias Colorretais/patologia , Imunidade Inata/imunologia , Imunidade Inata/fisiologia , Neoplasias Colorretais/epidemiologia , Neoplasias Colorretais/prevenção & controle , Fusobactérias/imunologia , Fusobactérias/isolamento & purificação , Bacteroides/patogenicidade , Actinobacteria/isolamento & purificação , Proteobactérias
9.
Med. oral patol. oral cir. bucal (Internet) ; 19(2): 184-191, mar. 2014. tab
Artigo em Inglês | IBECS | ID: ibc-121359

RESUMO

Objective: Several studies have focused on the relationship among serotype distribution, ethnical status and geographic populations, and periodontal conditions. Studies that have investigated the prevalence and the distribution of A. actinomycetemcomitans serotypes and the relation between the different serotypes of the bacterium and periodontal status were reviewed. Material and Methods: A systematic literature search for publications regarding the distribution of A. actinomycetemcomitans serotypes in subgingival samples of periodontitis patients and periodontally healthy subjects by employing polymerase chain reaction (PCR) was conducted. Results: From the 85 studies identified in the first analysis, only 12 met all inclusion and exclusion criteria. Clinical isolates from diverse geographic populations with different periodontal conditions were evaluated. Serotypes a, b and c were largely found, and serotype c was the most prevalent. They were isolated from various periodontal conditions, including aggressive periodontitis. Conclusions: The available literature suggests that serotypes a, b, and c are globally dominant, serotypes d and e are rare, and the prevalence of the most recently identified serotype f is still unknown. It is widely accepted that distribution patterns of A. actinomycetemcomitans vary among subjects of different ethnicity and geographic regions. The correlation of different serotypes with various periodontal conditions remains unclear (AU)


Assuntos
Humanos , Actinobacteria/isolamento & purificação , Doenças Periodontais/microbiologia , Índice Periodontal
10.
Int. microbiol ; 16(1): 17-25, mar. 2013. ilus, tab
Artigo em Inglês | IBECS | ID: ibc-114741

RESUMO

Fungus-growing ants associate with multiple symbiotic microbes, including Actinobacteria for production of antibiotics. The best studied of these bacteria are within the genus Pseudonocardia, which in most fungus-growing ants are conspicuously visible on the external cuticle of workers. However, given that fungus-growing ants in the genus Atta do not carry visible Actinobacteria on their cuticle, it is unclear if this genus engages in the symbiosis with Pseudonocardia. Here we explore whether improving culturing techniques can allow for successful isolation of Pseudonocardia from Atta cephalotes leaf-cutting ants. We obtained Pseudonocardia from 9 of 11 isolation method/colony component combinations from all 5 colonies intensively sampled. The most efficient technique was bead-beating workers in phosphate buffer solution, then plating the suspension on carboxymethylcellulose medium. Placing these strains in a fungus-growing ant-associated Pseudonocardia phylogeny revealed that while some strains grouped with clades of Pseudonocardia associated with other genera of fungus-growing ants, a large portion of the isolates fell into two novel phylogenetic clades previously not identified from this ant-microbe symbiosis. Our findings suggest that Pseudonocardia may be associated with Atta fungus-growing ants, potentially internalized, and that localizing the symbiont and exploring its role is necessary to shed further light on the association (AU)


No disponible


Assuntos
Animais , Formigas/microbiologia , Actinomycetales/patogenicidade , Simbiose , Actinobacteria/patogenicidade , Fungos/patogenicidade , Filogenia
11.
Int. microbiol ; 15(1): 17-32, mar. 2012. ilus, tab
Artigo em Inglês | IBECS | ID: ibc-102989

RESUMO

From specimens of the bryozoan Membranipora membranacea collected in the Baltic Sea, bacteria were isolated on four different media, which significantly increased the diversity of the isolated groups. All isolates were classified according to 16S rRNA gene sequence analysis and tested for antimicrobial properties using a panel of five indicator strains and six different media. Each medium featured a unique set of isolated phylotypes, and a phylogenetically diverse collection of isolates was obtained. A total of 96 isolates were assigned to 49 phylotypes and 29 genera. Only one-third of the members of these genera had been isolated previously from comparable sources. The isolates were affiliated with Alpha- and Gammaproteobacteria, Bacilli, and Actinobacteria. A comparable large portion of up to 22 isolates, i.e., 15 phylotypes, probably represent new species. Likewise, 47 isolates (approximately 50%) displayed antibiotic activities, mostly against grampositive indicator strains. Of the active strains, 63.8 % had antibiotic traits only on one or two of the growth media, whereas only 12.7 % inhibited growth on five or all six media. The application of six different media for antimicrobial testing resulted in twice the number of positive hits as obtained with only a single medium. The use of different media for the isolation of bacteria as well as the variation of media considered suitable for the production of antibiotic substances significantly enhanced both the number of isolates obtained and the proportion of antibiotic active cultures. Thus the approach described herein offers an improved strategy in the search for new antibiotic compounds (AU)


No disponible


Assuntos
Briozoários/microbiologia , Amilases/genética , Actinobacteria/isolamento & purificação , Meios de Cultura/análise , Alphaproteobacteria/isolamento & purificação , Gammaproteobacteria/isolamento & purificação
12.
Int. microbiol ; 14(2): 83-93, jun. 2011. ilus
Artigo em Inglês | IBECS | ID: ibc-93476

RESUMO

The bacterial microbiota from the whole gut of soldier and worker castes of the termite Reticulitermes grassei was isolated and studied. In addition, the 16S rDNA bacterial genes from gut DNA were PCR-amplified using Bacteria-selective primers, and the 16S rDNA amplicons subsequently cloned into Escherichia coli. Sequences of the cloned inserts were then used to determine closest relatives by comparison with published sequences and with sequences from our previous work. The clones were found to be affiliated with the phyla Spirochaetes, Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria, Synergistetes, Verrucomicrobia, and candidate phyla Termite Group 1 (TG1) and Termite Group 2 (TG2). No significant differences were observed with respect to the relative bacterial abundances between soldier and worker phylotypes. The phylotypes obtained in this study were compared with reported sequences from other termites, especially those of phylotypes related to Spirochaetes, Wolbachia (an Alphaproteobacteria), Actinobacteria, and TG1. Many of the clone phylotypes detected in soldiers grouped with those of workers. Moreover, clones CRgS91 (soldiers) and CRgW68 (workers), both affiliated with ‘Endomicrobia’, were the same phylotype. Soldiers and workers also seemed to have similar relative protist abundances. Heterotrophic, poly-β-hydroxyalkanoate-accumulating bacteria were isolated from the gut of soldiers and shown to be affiliated with Actinobacteria and Gammaproteobacteria. We noted that Wolbachia was detected in soldiers but not in workers. Overall, the maintenance by soldiers and workers of comparable axial and radial redox gradients in the gut is consistent with the similarities in the prokaryotes and protists comprising their microbiota (AU)


No disponible


Assuntos
Animais , Gástrula/microbiologia , Biota , Isópteros/patogenicidade , Spirochaetales/isolamento & purificação , Proteobactérias/isolamento & purificação , Bacteroidetes/isolamento & purificação , Actinobacteria/isolamento & purificação
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA