Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 6 de 6
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
J R Soc Interface ; 12(104): 20141225, 2015 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-25631569

RESUMO

Plants sense their environment by producing electrical signals which in essence represent changes in underlying physiological processes. These electrical signals, when monitored, show both stochastic and deterministic dynamics. In this paper, we compute 11 statistical features from the raw non-stationary plant electrical signal time series to classify the stimulus applied (causing the electrical signal). By using different discriminant analysis-based classification techniques, we successfully establish that there is enough information in the raw electrical signal to classify the stimuli. In the process, we also propose two standard features which consistently give good classification results for three types of stimuli--sodium chloride (NaCl), sulfuric acid (H2SO4) and ozone (O3). This may facilitate reduction in the complexity involved in computing all the features for online classification of similar external stimuli in future.


Assuntos
Fenômenos Fisiológicos Vegetais , Plantas/metabolismo , Algoritmos , Simulação por Computador , Análise Discriminante , Eletricidade , Solanum lycopersicum/fisiologia , Modelos Estatísticos , Ozônio , Reprodutibilidade dos Testes , Processamento de Sinais Assistido por Computador , Cloreto de Sódio/química , Poluentes do Solo/química , Processos Estocásticos , Ácidos Sulfúricos/química
2.
J R Soc Interface ; 12(102): 20141036, 2015 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-25392401

RESUMO

In nature, biofilms are the most common form of bacterial growth. In biofilms, bacteria display coordinated behaviour to perform specific functions. Here, we investigated electrical signalling as a possible driver in biofilm sociobiology. Using a multi-electrode array system that enables high spatio-temporal resolution, we studied the electrical activity in two biofilm-forming strains and one non-biofilm-forming strain. The action potential rates monitored during biofilm-forming bacterial growth exhibited a one-peak maximum with a long tail, corresponding to the highest biofilm development. This peak was not observed for the non-biofilm-forming strain, demonstrating that the intensity of the electrical activity was not linearly related to the bacterial density, but was instead correlated with biofilm formation. Results obtained indicate that the analysis of the spatio-temporal electrical activity of bacteria during biofilm formation can open a new frontier in the study of the emergence of collective microbial behaviour.


Assuntos
Bactérias/metabolismo , Biofilmes , Eletroquímica/instrumentação , Potenciais de Ação , Bacillus , Fenômenos Fisiológicos Bacterianos , Eletroquímica/métodos , Eletrodos , Escherichia coli , Análise em Microsséries , Polímeros/química , Pseudomonas , Transdução de Sinais , Temperatura
3.
Genome Announc ; 1(1)2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23469336

RESUMO

We report the draft genome sequence of Pseudomonas alcaliphila 34, a Cr(VI)-hyperresistant and biofilm-producing bacterium that might be used for the bioremediation of chromate-polluted soils. The genome sequence might be helpful in exploring the mechanisms involved in chromium resistance and biofilm formation.

4.
BMC Microbiol ; 12: 78, 2012 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-22607312

RESUMO

BACKGROUND: Plant-associated bacterial communities caught the attention of several investigators which study the relationships between plants and soil and the potential application of selected bacterial species in crop improvement and protection. Medicago sativa L. is a legume crop of high economic importance as forage in temperate areas and one of the most popular model plants for investigations on the symbiosis with nitrogen fixing rhizobia (mainly belonging to the alphaproteobacterial species Sinorhizobium meliloti). However, despite its importance, no studies have been carried out looking at the total bacterial community associated with the plant. In this work we explored for the first time the total bacterial community associated with M. sativa plants grown in mesocosms conditions, looking at a wide taxonomic spectrum, from the class to the single species (S. meliloti) level. RESULTS: Results, obtained by using Terminal-Restriction Fragment Length Polymorphism (T-RFLP) analysis, quantitative PCR and sequencing of 16 S rRNA gene libraries, showed a high taxonomic diversity as well as a dominance by members of the class Alphaproteobacteria in plant tissues. Within Alphaproteobacteria the families Sphingomonadaceae and Methylobacteriaceae were abundant inside plant tissues, while soil Alphaproteobacteria were represented by the families of Hyphomicrobiaceae, Methylocystaceae, Bradyirhizobiaceae and Caulobacteraceae. At the single species level, we were able to detect the presence of S. meliloti populations in aerial tissues, nodules and soil. An analysis of population diversity on nodules and soil showed a relatively low sharing of haplotypes (30-40%) between the two environments and between replicate mesocosms, suggesting drift as main force shaping S. meliloti population at least in this system. CONCLUSIONS: In this work we shed some light on the bacterial communities associated with M. sativa plants, showing that Alphaproteobacteria may constitute an important part of biodiversity in this system, which includes also the well known symbiont S. meliloti. Interestingly, this last species was also found in plant aerial part, by applying cultivation-independent protocols, and a genetic diversity analysis suggested that population structure could be strongly influenced by random drift.


Assuntos
Bactérias/classificação , Biota , Medicago sativa/microbiologia , Bactérias/genética , Análise por Conglomerados , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Dados de Sequência Molecular , Filogenia , Polimorfismo de Fragmento de Restrição , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
5.
Res Microbiol ; 162(8): 747-55, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21807093

RESUMO

Bacteria are known to adopt complex metabolic strategies in an effort to counteract the impact of numerous toxic compounds. In this study, a Cr(VI)-sensitive mutant of the Cr(VI)-hyperresistant bacterium Pseudomonas corrugata 28, obtained by insertional mutagenesis using the EZ-Tn5™ Tnp, was employed to gain a greater understanding of Cr(VI) resistance in bacteria. The insertion of the transposon, which occurred 16 bp upstream from the start codon of an ORF encoding a soluble pyridine nucleotide transhydrogenase (STH), negatively affected expression of the sth gene. The compromised expression of the sth gene in the mutant had two main effects on the pyridine nucleotide pools: (i) a decrease in NADPH and NADH fractions with a consequent shift in the redox state toward oxidation; and (ii) a decrease in the total concentration of the pyridine nucleotides. In the absence of a suitable pool of NADPH, the mutant failed to sustain an effective defense against the oxidative stress induced by Cr(VI).


Assuntos
Proteínas de Bactérias/genética , Cromo/farmacologia , Mutação , NADP Trans-Hidrogenases/genética , Pseudomonas/efeitos dos fármacos , Pseudomonas/enzimologia , Proteínas de Bactérias/metabolismo , Mutagênese Insercional , NADP Trans-Hidrogenases/metabolismo , Estresse Oxidativo , Pseudomonas/genética , Pseudomonas/metabolismo , Piridinas/metabolismo
6.
J Microbiol Methods ; 86(2): 258-61, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21664388

RESUMO

Phenotype MicroArray (PM) permits the characterisation of bacteria under nearly 2000 culture conditions. The PM standard procedure for the chemical sensitivity analysis of Gram-positive bacteria failed in the analysis of Streptococcus thermophilus. Therefore, we developed an efficient and reproducible protocol to obtain a chemically sensitive profile of S. thermophilus using PM.


Assuntos
Antibacterianos/farmacologia , Análise em Microsséries/métodos , Streptococcus thermophilus/efeitos dos fármacos , Testes de Sensibilidade Microbiana/métodos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...