Dinámica espaciotemporal de los procesos de desertificación y revegetalización natural en el enclave seco de La Tatacoa, Colombia

En el desierto de La Tatacoa, la degradación del suelo y la pérdida de productividad son atribuidas a factores ambientales y antrópicos. En este artículo se evalúa la dinámica espaciotemporal de coberturas en un periodo no continuo de 23 anos (1987-2001-2010) identificando áreas de perdida y de recuperación de vegetación. Se aplicaron correcciones geométricas y radiométricas, además, se realizó un análisis cuantitativo aplicando clasificación supervisada a las imágenes Landsat. Las dinámicas espaciotemporales se identificaron a través de matrices de cambio y el índice Kappa. El análisis multitemporal mostro disminución de las áreas de suelos degradados (16,7%) y aumento de la cobertura vegetal (13,4%), lo que evidencia un proceso de recuperación a una tasa de 124 ha/ano. Las áreas de vegetación natural estables y de mayor variación positiva de vegetación natural están localizadas en el norte, nororiente y oriente; la variación negativa se observa en la región adyacente al rio Magdalena. Estos resultados son la base para nuevas investigaciones sobre los factores bióticos, abióticos y socioeconómicos que han generado la recuperación de áreas de vegetación natural en algunos sectores y la desertificación en otros, y se encaminan a plantear medidas sectorizadas como la restauración ecológica, los sistemas silvopastoriles y agroforestales acordes con la problemática social y ambiental en un contexto de cambio climático. Ideas destacadas: artículo de investigación sobre la dinámica de las coberturas en el enclave seco de la Tatacoa con aplicaciones sig a partir de imágenes Landsat para determinar el proceso de desertificación y la revegetalización natural que ha tenido lugar en un periodo de 23 años.

Dinámica espacio-temporal de los procesos de desertificación y revegetalización natural en el enclave seco de La Tatacoa, Colombia

Problem. Soil degradation and diminished production in the desert of La Tatacoa are attributed to both environmental and anthropic factors. This article assesses the spatiotemporal dynamics of soil coverage in a discontinuous period of 23 years (1987-2001-2010), identifying areas of loss and recovery of vegetation. Methodology. Geometric and radiometric corrections were applied, in addition, a quantitative analysis was performed by applying supervised classification to Landsat images. Spatiotemporal dynamics were identified through change matrices and the Kappa index. Results. Multitemporal analysis showed a decrease in the areas of degraded soils (16.7%) and an increase in vegetal coverage (13.4%), which evinces a recovery process of 124 ha/year. The areas of stable natural vegetation and of greatest positive variation in the vegetal coverage are located to the north, northeast, and east, while the negative variation can be observed in the region adjacent to the Magdalena river. Conclusion. These results serve as the basis for new research on the biotic, abiotic, and socioeconomic factors that have generated the recovery of natural vegetation areas in some sectors and desertification in others. They seek to contribute to the formulation of sectorized measures such as ecological restoration as well as silvopastoral and agroforestry systems in according to social and environmental issues in a context of climate change.Problema. No deserto da Tatacoa, a degradação do solo e a perda de produtividade são atribuídas a fatores ambientais e antrópicos. Neste artigo, avaliou-se a dinâmica espaço-temporal de cobertura em um período não contínuo de 23 anos (1987-2001-2010) e identificou-se áreas de perda e recuperação de vegetação. Metodologia. Foram aplicadas correções geométricas e radiométricas, além disso, foi realizado uma análise quantitativa aplicando uma classificação supervisionada às imagens Landsat. As dinâmicas espaço-temporais foram identificadas através de matrizes de mudança e do índice Kappa. Resultados. A análise multitemporal mostrou uma diminuição nas áreas de solos degradados (16,7%) e um aumento na cobertura vegetal (13,4%), o que evidencia um processo de recuperação a uma taxa de 124 ha/ano. As áreas de vegetação natural estáveis e de maior variação positiva de vegetação natural estão localizadas no norte, nordeste e leste; a variação negativa é observada na região adjacente ao rio Magdalena. Resultados. Esses resultados são a base para novas pesquisas sobre os fatores bióticos, abióticos e socioeconômicos que geraram a recuperação de áreas de vegetação natural em algumas áreas e de desertificação em outras, e são usados para propor medidas setorizadas, como a restauração ecológica, os sistemas silvopastoris e os agroflorestais de acordo com a problemática social e ambiental em um contexto de mudança climática.Problema. En el desierto de La Tatacoa, la degradación del suelo y la pérdida de productividad son atribuidas a factores ambientales y antrópicos. En este artículo se evalúa la dinámica espacio-temporal de coberturas en un periodo no continuo de 23 años (1987-2001-2010) identificando áreas de pérdida y de recuperación de vegetación. Metodología. Se aplicaron correcciones geométricas y radiométricas, además, se realizó un análisis cuantitativo aplicando clasificación supervisada a las imágenes Landsat. Las dinámicas espacio-temporales se identificaron a través de matrices de cambio y el índice Kappa. Resultados. El análisis multitemporal mostró disminución de las áreas de suelos degradados (16,7%) y aumento de la cobertura vegetal (13,4%), lo que evidencia un proceso de recuperación a una tasa de 124 ha/año. Las áreas de vegetación natural estables y de mayor variación positiva de vegetación natural están localizadas en el norte, nororiente y oriente; la variación negativa se observa en la región adyacente al río Magdalena. Conclusión. Estos resultados son la base para nuevas investigaciones sobre los factores bióticos, abióticos y socioeconómicos que han generado la recuperación de áreas de vegetación natural en algunos sectores y la desertificación en otros, y se encaminan a plantear medidas sectorizadas como la restauración ecológica, los sistemas silvopastoriles y agroforestales acordes con la problemática social y ambiental en un contexto de cambio climático.Ideas destacadas: artículo de investigación sobre la dinámica de las coberturas en el enclave seco de la Tatacoa con aplicaciones sig a partir de imágenes Landsat para determinar el proceso de desertificación y la revegetalización natural que ha tenido lugar en un periodo de 23 años.

Compilation of the Antimicrobial Compounds Produced by <i>Burkholderia</i> Sensu Stricto

Due to the increase in multidrug-resistant microorganisms, the investigation of novel or more efficient antimicrobial compounds is essential. The World Health Organization issued a list of priority multidrug-resistant bacteria whose eradication will require new antibiotics. Among them, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacteriaceae are in the “critical” (most urgent) category. As a result, major investigations are ongoing worldwide to discover new antimicrobial compounds. Burkholderia, specifically Burkholderia sensu stricto, is recognized as an antimicrobial-producing group of species. Highly dissimilar compounds are among the molecules produced by this genus, such as those that are unique to a particular strain (like compound CF66I produced by Burkholderia cepacia CF-66) or antimicrobials found in a number of species, e.g., phenazines or ornibactins. The compounds produced by Burkholderia include N-containing heterocycles, volatile organic compounds, polyenes, polyynes, siderophores, macrolides, bacteriocins, quinolones, and other not classified antimicrobials. Some of them might be candidates not only for antimicrobials for both bacteria and fungi, but also as anticancer or antitumor agents. Therefore, in this review, the wide range of antimicrobial compounds produced by Burkholderia is explored, focusing especially on those compounds that were tested in vitro for antimicrobial activity. In addition, information was gathered regarding novel compounds discovered by genome-guided approaches

Broad-spectrum antimicrobial activity by Burkholderia cenocepacia TAtl-371, a strain isolated from the tomato rhizosphere

The Burkholderia cepacia complex (Bcc) comprises a group of 24 species, many of which are opportunistic pathogens of immunocompromised patients and also are widely distributed in agricultural soils. Several Bcc strains synthesize strainspecific antagonistic compounds. In this study, the broad killing activity of B. cenocepacia TAtl-371, a Bcc strain isolated from the tomato rhizosphere, was characterized. This strain exhibits a remarkable antagonism against bacteria, yeast and fungi including other Bcc strains, multidrug-resistant human pathogens and plant pathogens. Genome analysis of strain TAtl-371 revealed several genes involved in the production of antagonistic compounds: siderophores, bacteriocins and hydrolytic enzymes. In pursuit of these activities, we observed growth inhibition of Candida glabrata and Paraburkholderia phenazinium that was dependent on the iron concentration in the medium, suggesting the involvement of siderophores. This strain also produces a previously described lectin-like bacteriocin (LlpA88) and here this was shown to inhibit only Bcc strains but no other bacteria. Moreover, a compound with an m/z 391.2845 with antagonistic activity against Tatumella terrea SHS 2008T was isolated from the TAtl-371 culture supernatant. This strain also contains a phage-tail-like bacteriocin (tailocin) and two chitinases, but the activity of these compounds was not detected. Nevertheless, the previous activities are not responsible for the whole antimicrobial spectrum of TAtl-371 seen on agar plates, suggesting the presence of other compounds yet to be found. In summary, we observed a diversified antimicrobial activity for strain TAtl-371 and believe it supports the biotechnological potential of this Bcc strain as a source of new antimicrobials.status: Published onlin

Broad-spectrum antimicrobial activity by Burkholderia cenocepacia TAtl-371, a strain isolated from the tomato rhizosphere.

The Burkholderia cepacia complex (Bcc) comprises a group of 24 species, many of which are opportunistic pathogens of immunocompromised patients and also are widely distributed in agricultural soils. Several Bcc strains synthesize strain-specific antagonistic compounds. In this study, the broad killing activity of B. cenocepacia TAtl-371, a Bcc strain isolated from the tomato rhizosphere, was characterized. This strain exhibits a remarkable antagonism against bacteria, yeast and fungi including other Bcc strains, multidrug-resistant human pathogens and plant pathogens. Genome analysis of strain TAtl-371 revealed several genes involved in the production of antagonistic compounds: siderophores, bacteriocins and hydrolytic enzymes. In pursuit of these activities, we observed growth inhibition of Candida glabrata and Paraburkholderia phenazinium that was dependent on the iron concentration in the medium, suggesting the involvement of siderophores. This strain also produces a previously described lectin-like bacteriocin (LlpA88) and here this was shown to inhibit only Bcc strains but no other bacteria. Moreover, a compound with an m/z 391.2845 with antagonistic activity against Tatumella terrea SHS 2008T was isolated from the TAtl-371 culture supernatant. This strain also contains a phage-tail-like bacteriocin (tailocin) and two chitinases, but the activity of these compounds was not detected. Nevertheless, the previous activities are not responsible for the whole antimicrobial spectrum of TAtl-371 seen on agar plates, suggesting the presence of other compounds yet to be found. In summary, we observed a diversified antimicrobial activity for strain TAtl-371 and believe it supports the biotechnological potential of this Bcc strain as a source of new antimicrobials

Draft Genome Sequence of Heavy Metal-Resistant Cupriavidus alkaliphilus ASC-732T, Isolated from Agave Rhizosphere in the Northeast of Mexico.

Cupriavidus alkaliphilus ASC-732(T) was isolated from the rhizosphere of agave plant growing in alkaline soils in San Carlos, Tamaulipas, Mexico. The species is able to grow in the presence of arsenic, zinc, and copper. The genome sequence of strain ASC-732(T) is 6,125,055&nbsp;bp with 5,586 genes and an average G+C content of 67.81%