{"id":143020,"date":"2013-08-29T16:30:06","date_gmt":"2013-08-29T15:30:06","guid":{"rendered":"http:\/\/www.madrimasd.org\/blogs\/universo\/?p=143020"},"modified":"2013-08-29T16:30:06","modified_gmt":"2013-08-29T15:30:06","slug":"bacterias-del-suelo-y-erosion-eolica","status":"publish","type":"post","link":"https:\/\/www.madrimasd.org\/blogs\/universo\/2013\/08\/29\/143020","title":{"rendered":"Bacterias del Suelo y Erosi\u00f3n E\u00f3lica"},"content":{"rendered":"

Mediante t\u00e9cnicas de Pirosecuenciaci\u00f3n<\/a> y haciendo uso de t\u00faneles de viento<\/a>, investigaciones recientes han mostrado el efecto de la erosi\u00f3n e\u00f3lica<\/strong> <\/span>de diferente intensidad sobre el arrastre part\u00edculas del suelo de<\/span> diferente tama\u00f1o, as\u00ed como el tipo de las bacterias que eran arrancadas del suelo<\/span><\/strong>. La Pirosecuenciaci\u00f3n<\/a> sirve<\/strong><\/span> con vistas a\u00a0determinar el DNA global de las muestras, permitiendo discernir entre los distintos de los grandes grupos bacterianos. Por su parte, los de t\u00faneles de viento<\/a> se ha utilizado con el prop\u00f3sito de\u00a0simular el arrastre de materiales (inorg\u00e1nicos, org\u00e1nicos y biog\u00e9nicos) bajo diferente reg\u00edmenes de viento sobre tipos de suelos y sedimentos de naturaleza variada<\/strong><\/span>.\u00a0 As\u00ed se ha podido demostrar que las comunidades bacterianas que albergan las part\u00edculas de mayor tama\u00f1o son distintas de las contenidas en las de\u00a0menor calibre<\/strong><\/span>. Del hecho, seg\u00fan los autores, se demuestra que estos diferentes micro-h\u00e1bitats atesoran comunidades distintas<\/strong><\/span>, por lo que seg\u00fan el viento arrastre uno u otro tipo de part\u00edculas tambi\u00e9n exportar\u00e1 a otros lugares en donde se depositen microrganismos diferentes, empobreciendo los horizontes superficiales del suelo en unos u otros<\/strong><\/span>. Cabe recordar que distintas clases de bacterias desempe\u00f1an diferentes roles en el medio ed\u00e1fico, por lo que resulta interesante conocer cuales son m\u00e1s susceptibles de volar a otros lares, seg\u00fan las condiciones ambientales y edafotaxa que se den en un determinado enclave, afectando al metabolismo del suelo de manera diferencial<\/strong>.<\/span> As\u00ed por ejemplo, las Proteobacteria<\/em><\/a>, <\/em>que desempe\u00f1an un papel sumamente importante en los ciclos del carbono y el nitr\u00f3geno, aparecen fundamentalmente asociadas a las fracciones granulom\u00e9tricas gruesas<\/strong><\/span> del suelo. Por el contrario, las fracciones finas se caracterizan por la gran cantidad<\/strong> <\/span>que atesoran de Bacteroidetes<\/a><\/em> y otros microbios muy resistentes a condiciones extremas, tales como la sequedad o la alta incidencia de radiaciones gama. Tambi\u00e9n cabe recordar que la exportaci\u00f3n por el viento afecta de manera diferente a las part\u00edculas del suelo en funci\u00f3n de su tama\u00f1o. Las mayores, por su peso, caen r\u00e1pidamente a tierra, por lo que apenas suelen distanciarse del lugar de donde fueron erosionadas, mientas que las finas pueden viajar suspendidas en el a\u00edre y ser depositadas a cientos o miles de kil\u00f3metros de distancia, lo cual encaja con las propiedades previamente mentadas.\u00a0 En base a estos hallazgos, los investigadores que llevaron a cabo este estudio defienden que la superficie del suelo afectada por la erosi\u00f3n e\u00f3lica pierde diversidad microbiana, aunque de forma diferencial<\/strong><\/span>. Del mismo modo, las Actinobacterias<\/em><\/a> tambi\u00e9n muy importantes en el metabolismo del medio ed\u00e1fico, y la formaci\u00f3n de esas\u00a0 estructuras denominadas agregados, suelen<\/span> resistir la acci\u00f3n del viento permaneciendo arraigadas al lugar donde nacieron<\/span><\/strong>.\u00a0 Con independencia de los suelos bajo condiciones naturales \u00e1ridas y semi\u00e1ridas<\/strong><\/span>, que suelen padecer frecuentemente de la falta de cobertura vegetal, una gran parte de las tierras agr\u00edcolas del mundo, durante alguna estaci\u00f3n permanecen desnudas, siendo f\u00e1cil presa de la erosi\u00f3n cuando las condiciones meteorol\u00f3gicas la propician<\/strong><\/span>.<\/p>\n

\u00a0\"proteobacteria\"<\/p>\n

Proteobacterias. Fuente: Universidad de Auckland<\/a><\/p>\n

Finalmente, este tipo de an\u00e1lisis, seg\u00fan los autores, pueden servir tanto, para entender\u00a0la huella digital microbiana tras un impacto ambiental<\/strong> <\/span>y as\u00ed evaluar sus repercusiones, como reconocer<\/span> la importancia de enriquecer el suelo en materia en materia org\u00e1nica, mediante una gesti\u00f3n adecuada que evite o minimice el tiempo en el que el suelo se encuentra desnudo y evitar la perdida de microrganismos que pueden afectar negativamente a la hora de que\u00a0el medio ed\u00e1fico mantenga un metabolismo saludable<\/strong><\/span>. El estudio me parece interesante y original, en especial por utilizar los t\u00faneles de viento<\/a> para simular reg\u00edmenes de perturbaci\u00f3n del medio ed\u00e1fico bajo condiciones meteorol\u00f3gicas dispares. Ahora bien, aun queda mucho por hacer con vistas a alcanzar conclusiones menos generales y ambiguas, es decir, m\u00e1s jugosas. Recordemos que los suelos h\u00famedos son mucho m\u00e1s resistentes que los que se encuentran secos, frente a los agentes erosivos e\u00f3licos. \u00bfPodr\u00edamos pues inferir que los suelos con horizontes superficies ricos en arcillas son menos resilientes frente\u00a0la erosi\u00f3n que los que atesoran fracciones gruesas en abundancia?<\/span><\/strong>. Con toda franqueza, considero que hacen falta muchas m\u00e1s pruebas como para poder corroborar tal aserto.<\/p>\n

\"actinobacterias\"<\/p>\n

Actinobacterias. Fuente: CB TV<\/a><\/p>\n

 <\/p>\n

Juan Jos\u00e9 Ib\u00e1\u00f1ez\u00a0<\/span> <\/strong><\/p>\n

Lo que el viento se llevo\u2026\u2026..<\/em><\/span><\/p>\n

\"bacrerioidetes-fuente-microbe-wiki-marivarga_tractuosa\"<\/span><\/p>\n

Bacteriodidetes. Fuente: Microbe Wiki<\/a><\/p>\n

Agricultural Bacteria: Blowing in the Wind<\/strong><\/a><\/h3>\n

ScienceDaily (May 9, 2012)<\/em><\/strong> <\/span>\u2014 It was all too evident during the Dust Bowl what a disastrous impact wind can have on dry, unprotected topsoil. Now a new study has uncovered a less obvious, but still troubling, effect of wind: Not only can it carry away soil particles, but also the beneficial microbes that help build soil, detoxify contaminants, and recycle nutrients<\/strong>.<\/p>\n

Using a powerful DNA sequencing technique, called pyrosequencing, a team led by USDA-ARS<\/strong> scientists Terrence Gardner and Veronica Acosta-Mart\u00ednez analyzed the bacterial diversity in three Michigan agricultural soils, and in two eroded sediments generated from these soils during a wind tunnel experiment<\/strong>: coarse particles and fine dust. Not only were the microbial assemblages on the coarse particles distinct from those on the dust<\/strong>, report the scientists in the current issue of the Journal of Environmental Quality<\/em><\/strong>, but the two types of eroded sediments were each enriched in certain groups of microbes compared with the parent soil, as well<\/strong>.<\/p>\n

The findings suggest that specific bacteria inhabit specific locations in soil — and thus different groups and species can be carried away depending on the kinds of particles that erode<\/strong>. \u00abIt’s important to know which microbes are being lost from soil<\/strong>,\u00bb says Acosta-Mart\u00ednez, a soil microbiologist and biochemist at the USDA-ARS Cropping Systems Laboratory in Lubbock, TX, \u00abbecause different microbes have different roles in soil processes<\/strong>.\u00bb<\/p>\n

For example, the <\/strong>Proteobacteria<\/em><\/strong> — a diverse group critical to carbon and nitrogen cycling — were more associated in the study with eroded, coarse particles<\/strong> (those larger than 106 microns in size) than with the fine dust<\/strong>. Similarly, the dust housed its own community, in this <\/strong>case Bacteroidetes<\/em> <\/strong>and other bacteria that are known to tolerate extreme dryness, gamma radiation, and other harsh conditions<\/strong> that may develop on dust particles as they float through the air, says Gardner, a postdoctoral researcher who is also affiliated with Alabama A&M University.<\/p>\n

What this means is that wind erosion can both reduce the overall microbial diversity in farm fields, as well as deplete topsoil of specific groups of essential bacteria<\/strong>, say the researchers. At the same time, certain important groups, such as Actinobacteria<\/em> that <\/strong>promote soil aggregation<\/strong>, remained in the parent soil despite the erosive conditions generated in the wind tunnel. And while fine dust can travel extremely long distances, coarse particles rarely move more than 20 feet, suggesting that they — and their associated microbes<\/strong> — should be fairly easy to retain with cover cropping and other soil conservation measures<\/strong>, Acosta-Mart\u00ednez notes.<\/p>\n

Helping farmers and land managers adopt practices that better conserve soil is one of the main goals of the USDA-ARS team’s work, which also includes Ted Zobeck, Scott Van Pelt, Matt Baddock, and Francisco Calder\u00f3n. In the Southern High Plains region, for example, intense cultivation of soil combined with a semi-arid climate can result in serious wind erosion problems<\/strong>. In fact, last summer’s drought brought Dust Bowl-like conditions<\/strong> to the area, says Acosta-Mart\u00ednez.<\/p>\n

But \u00abwind erosion is a national problem,\u00bb she adds, with significant erosion occurring even in places where the growing season is humid and wet. Organic histosol soils in Michigan<\/strong> and many other parts of the country, for instance, are very susceptible to wind erosion<\/strong> when dry<\/strong>, especially since they’re usually intensively farmed and often left bare in winter<\/strong>. Cover cropping or crop rotations<\/strong> not only help keep these soils in place, but can also build soil organic matter, which in turn promotes soil aggregation, water penetration, and general soil health<\/strong>.<\/p>\n

It can take years, however<\/strong>, for farmers who’ve adopted new management practices to detect noticeable changes in levels of soil organic matter and other traditional soil quality measures. This is why Acosta-Martinez and Gardner have been analyzing soils with pyrosequencing<\/strong>, a method that yields a fingerprint of an entire microbial community, and well as identifies specific groups and species of bacteria based on their unique DNA sequences<\/strong>.<\/p>\n

In this study, these microbial signatures told the researchers what’s potentially being lost from soil during wind erosion events. But the fingerprints can be early indicators of positive outcomes, too.<\/p>\n

\u00abThe microbial component is one of the most sensitive signatures of changes in the soil<\/strong>,\u00bb says Acosta-Mart\u00ednez, because of microbes’ involvement in soil processes, such as carbon accumulation and biogeochemical cycling. \u00abSo, we’re looking for any shifts in these signatures that could lead us to think that there are benefits to the soil with alternative management<\/strong>.\u00bb<\/p>\n

Story Source: <\/strong>The above story is reprinted from materials<\/a> provided by American Society of Agronomy (ASA)<\/strong><\/a>, via Newswise.<\/p>\n

Journal Reference<\/strong>: Terrence Gardner, Veronica Acosta-Martinez, Francisco J. Calder\u00f3n, Ted M. Zobeck, Matthew Baddock, R. Scott Van Pelt, Zachary Senwo, Scot Dowd, Stephen Cox. Pyrosequencing Reveals Bacteria Carried in Different Wind-Eroded Sediments<\/strong>. Journal of Environment Quality<\/em>, 2012; 41 (3): 744 DOI: 10.2134<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

Mediante t\u00e9cnicas de Pirosecuenciaci\u00f3n y haciendo uso de t\u00faneles de viento, investigaciones recientes han mostrado el efecto de la erosi\u00f3n e\u00f3lica de diferente intensidad sobre el arrastre part\u00edculas del suelo de diferente tama\u00f1o, as\u00ed como el tipo de las bacterias que eran arrancadas del suelo. La Pirosecuenciaci\u00f3n sirve con vistas a\u00a0determinar el DNA global de las muestras, permitiendo discernir entre los distintos de los grandes grupos bacterianos. Por su parte, los de t\u00faneles de viento se ha utilizado con el prop\u00f3sito de\u00a0simular el arrastre de materiales (inorg\u00e1nicos, org\u00e1nicos y biog\u00e9nicos) bajo diferente reg\u00edmenes de viento sobre tipos de suelos y\u2026<\/p>\n","protected":false},"author":26,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"ngg_post_thumbnail":0},"categories":[596,590,586,589,585,598],"tags":[19827,19828,46833,2518,2683],"blocksy_meta":{"styles_descriptor":{"styles":{"desktop":"","tablet":"","mobile":""},"google_fonts":[],"version":4}},"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/posts\/143020"}],"collection":[{"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/users\/26"}],"replies":[{"embeddable":true,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/comments?post=143020"}],"version-history":[{"count":11,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/posts\/143020\/revisions"}],"predecessor-version":[{"id":144425,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/posts\/143020\/revisions\/144425"}],"wp:attachment":[{"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/media?parent=143020"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/categories?post=143020"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/tags?post=143020"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}