{"id":143534,"date":"2013-12-02T15:07:17","date_gmt":"2013-12-02T14:07:17","guid":{"rendered":"http:\/\/www.madrimasd.org\/blogs\/universo\/?p=143534"},"modified":"2013-12-02T15:07:17","modified_gmt":"2013-12-02T14:07:17","slug":"la-biomasa-microbiana-y-su-importancia-en-los-suelos","status":"publish","type":"post","link":"https:\/\/www.madrimasd.org\/blogs\/universo\/2013\/12\/02\/143534","title":{"rendered":"La biomasa microbiana y su importancia en los suelos"},"content":{"rendered":"

La nota de prensa que os ofrecemos hoy nos informa de la importancia de la materia org\u00e1nica de origen bacteriano en los suelos. as\u00ed como de\u00a0su papel en<\/strong><\/span> la estructura de los ecosistemas ed\u00e1ficos, fertilidad y secuestro de carbono atmosf\u00e9rico<\/strong><\/span>. Se trata de nuevas indagaciones que, en parte, cambian la percepci\u00f3n vigente, del rol desempe\u00f1ado por las sustancias h\u00famicas en los suelos<\/strong><\/span>. Toda novedad debe ser corroborada debidamente antes de incorporarse al corpus doctrinal de una disciplina, por lo que habr\u00e1 que esperar estudios posteriores con vistas a validar si se trata de \u201cciencia buena\u201d. Hasta la fecha los expertos sosten\u00edan que la mayor parte de la materia org\u00e1nica (SOM) de los suelos era de origen vegetal, con independencia del <\/strong><\/span>papel que finalmente pudieran desempe\u00f1ar otras fuentes. Sin embargo<\/strong><\/span>, lo que dice haber descubierto este esquipo de investigadores alemanes cuestiona tal tesis. De acuerdo con ellos la biomasa bacteriana y en especial la procedente de sus paredes celulares desempe\u00f1a un rol esencial, acumul\u00e1ndose en cantidades considerables, por lo que resultar\u00eda ser esencial no solo en la formaci\u00f3n de los agregados del suelo, sino en el almacenamiento de carbono<\/strong> <\/span>(y como corolario en su secuestro de la atmosf\u00e9rico<\/strong>, <\/strong><\/span><\/span>a largo plazo (…).<\/p>\n

\"mineralizacion-de-la-som-en-el-suelo\"<\/p>\n

Descomposici\u00f3n de la materia org\u00e1nica del suelo. Fuente: Maximum Yield<\/a><\/p>\n

De acuerdo a estos investigadores, buena parte de<\/strong> los restos vegetales<\/strong> <\/span>(los m\u00e1s f\u00e1ciles de metabolizar) ser\u00edan asimilados por las comunidades microbianas del suelo pasando a formar parte de su biomasa. M\u00e1s aun un 40% de la \u00faltima se transformar\u00eda en sustancias h\u00famicas resistentes a la mineralizaci\u00f3n. Al morir, fragmentos nanom\u00e9tricos<\/em> de estas paredes bacterianas se acumulan en el medio ed\u00e1fico<\/strong><\/span>. En tal proceso parecen intervenir \u201cde alguna manera\u201d los p\u00e9ptidos y \u00a0prote\u00ednas del citoplasma celular, que de este modo persisten en mayor medida en el suelo que<\/strong><\/span> otros componentes del microrganismo. Estos materiales permiten la formaci\u00f3n de pel\u00edculas moleculares org\u00e1nicas que cementan y estabilizan los componentes minerales del suelo, pero<\/strong> <\/span>tambi\u00e9n a ellas mismas (resistencia a la mineralizaci\u00f3n).<\/p>\n

Cuando los fragmentos de estas paredes celulares bacterianas se secan, pueden perder sus propiedades de goma cementante, endureci\u00e9ndose como el vidrio<\/strong><\/span>. Si con posterioridad el suelo se humedece de nuevo, tales fragmentos de SOM microbiano no pueden humectarse simult\u00e1neamente, requisito previo para su mineralizaci\u00f3n<\/span> <\/strong>por el ataque de otras bacterias. Tal mecanismo ofrecer\u00eda una explicaci\u00f3n m\u00e1s simple que las actuales hip\u00f3tesis<\/strong><\/span> a la hora de dar cuenta de la estabilizaci\u00f3n de compuestos de carbono que, en teor\u00eda, deber\u00edan ser f\u00e1cilmente degradables.<\/p>\n

\u00a0Al margen de an\u00e1lisis de laboratorio (microscopios electr\u00f3nicos de barrido is\u00f3topos de carbono estable, etc.,), estos bioqu\u00edmicos alemanes usan como campo de pruebas la formaci\u00f3n del suelo y sucesi\u00f3n\u00a0natural de la vegetaci\u00f3n<\/strong>\u00a0<\/span>(de musgos y l\u00edquenes a herb\u00e1ceas, de estas a matorrales, hasta que finalmente crece el arbolado) de un antiguo glaciar que se deshel\u00f3 hace unos 150 a\u00f1os<\/strong><\/span>. Y al hacerlo constataron que la cantidad de SOM bacteriano que rodea las part\u00edculas minerales incrementa sosteniblemente con el tiempo<\/strong><\/span>. Por lo tanto, una buena parte los restos vegetales se transforman con relativa rapidez en biomasa microbiana que da lugar a un incremento de fertilidad f\u00edsica<\/strong> <\/span>(estructura del suelo), que a su vez retroalimenta el crecimiento microbiano y como corolario la acumulaci\u00f3n de las mentadas nanopart\u00edculas de paredes bacterianas<\/strong><\/span>.<\/p>\n

En la nota de prensa no parece quedar muy claro (aunque hacia el final del texto se insin\u00faa algo) si todo este proceso tan solo afecta a las bacterias o tambi\u00e9n implica a otros microrganismos del suelo cuya abundancia nadie cuestiona como hongos, actinomicetos, levaduras y arqueas<\/strong><\/span>.<\/p>\n

\u00a0Los autores, dejando de ser originales, terminan su desiderata realzando la importancia de todo este proceso en el secuestro de carbono atmosf\u00e9rico, punto en el cual comenc\u00e9 a echarme una siesta sobre la consola de mi PC.<\/p>\n

\u00a0Pues bien, parte de toda esta narraci\u00f3n ya era conocida y en especial<\/strong> <\/span>el rol de del SOM de los microrganismos en la formaci\u00f3n y estabilizaci\u00f3n de agregados. \u201cDebo suponer\u201d que muchos detalles y las cantidades narradas s\u00ed son primicia cient\u00edfica<\/strong><\/span>, aunque como \u00a0mi bioqu\u00edmica del suelo se encuentra obsoleta (\u2026\u2026)<\/p>\n

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

Fertile Soil Doesn’t Fall from the Sky: Contribution of Bacterial Remnants to Soil Fertility Has Been Underestimated Until Now<\/strong><\/a><\/strong><\/h4>\n

\u00a0<\/strong>Sciencedaily Dec. 14, 2012<\/em><\/strong> <\/span>\u2014 Remains of dead bacteria have far greater meaning for soils than previously assumed. Around 40 per cent of the microbial biomass is converted to organic soil components<\/strong>, write researchers from the Helmholtz Centre for Environmental Research (UFZ), the Technische Universit\u00e4t Dresden (Technical University of Dresden) , the University of Stockholm, the Max-Planck-Institut f\u00fcr Entwicklungsbiologie (Max Planck Institute for Developmental Biology) and the Leibniz-Universit\u00e4t Hannover (Leibniz University Hannover) in the journal Biogeochemistry<\/em>.<\/p>\n

\u00a0Until now, it was assumed that the organic components of the soil were composed mostly of decomposed plant material which is directly converted to humic substances<\/strong>. In a laboratory experiment and in field testing the researchers have now refuted this thesis. Evidently the easily biologically degradable plant material is initially converted to microbial biomass which then provides the source material to soil organic matter<\/strong>.<\/p>\n

Soil organic matter represents the largest fraction of terrestrially bound carbon in the biosphere<\/strong>. The compounds therefore play an important role not only for soil fertility<\/strong> and agricultural yields. They are also one of the key factors controlling the concentration of carbon dioxide in the atmosphere<\/strong>. Climatic change can therefore be slowed down or accelerated, according to the management of the soil resource<\/strong>.<\/p>\n

In laboratory incubation experiment<\/strong>, the researchers initially labelled model bacteria<\/strong> with the stable isotope 13<\/sup>C<\/strong> and introduced the bacteria to soil deriving from the long-term cultivation experiment \u00abEwiger Roggenbau\u00bb in Halle\/Saale. Following the incubation time of 224 days the fate of the carbon of bacterial origin was determined. \u00abAs a result we found fragments of bacterial cell walls in sizes of up to 500 x 500 nanometres throughout our soil samples<\/strong>. Such fragments have also been observed in other studies, but have never been identified or quantified,\u00bb declares Professor Matthias K\u00e4stner of the UFZ. The accumulation of the bacterial cell wall fragments appears to be supported by peptides and proteins from the liquid interior of the cells, which remain to a greater extent in the soil than other cell components. These materials enable the formation of a film of organic molecules on the mineral components of the soil, on which the carbon from the dead bacteria is accumulated and stabilised<\/strong>.<\/p>\n

When the fragments of the bacterial cell walls dry out, they may lose their rubber-like properties and can harden like glass<\/strong>. If the soil subsequently becomes moist again<\/strong>, however, under certain circumstances they cannot be re-wetted — an important prerequisite for their degradation<\/strong> by other bacteria. This would provide the simplest explanation for the stabilisation of theoretically easily degradable carbon compounds in soil<\/strong>. \u00abThis new approach explains many properties of organic soil components which were previously viewed as contradictory,<\/strong>\u00bb says Matthias K\u00e4stner. In the late 1990s, K\u00e4stner and his team arrived at this idea on the basis of earlier investigations on the degradation of environmental contaminants like anthracene in polluted soils of former gas work sites. In these investigations, isotopic analyses revealed bound carbon residues which have been of bacterial origin. With the support of the German Research Foundation (Deutsche Forschungsgemeinschaft; DFG), from 2000 on they began to follow up this clue within the scope of two joint research programmes.<\/p>\n

Following the laboratory experiment, the hypothesis was tested in field research<\/strong>. In summer of 2009 the researchers took soil samples in the forefield of the Damma Glacier in the Swiss Canton Uri. In the course of the last 150 years glacier has retreated by around one kilometre. In its place granite rock remained behind, which was gradually recolonised by living organisms accompanied by soil development. Following the formation of new soil the first plants, such as mosses and grasses, were followed by bushes and, later, also by trees. In the meantime, the Damma Glacier, on which a broad range of studies is being conducted, has therefore become an important outdoor laboratory not only for climate researchers, but for ecologists as well. The soil investigated with the samples was between 0 and 120 years old and thus allowed insight into early processes of soil development. Scanning electron microscopic investigations<\/strong> which followed at the Max Planck Institute for Developmental Biology in T\u00fcbingen also indicated that the covering of the soil mineral particles by a film composed of bacterial cell wall residues had increased with the soil age<\/strong>. The results of the outdoor investigations therefore confirmed the hypothesis and the laboratory results<\/strong>. This new knowledge was ultimately made possible by recent advances in scanning electron microscopy, which in the meantime enable the identification and evaluation of the soil nano-components<\/strong>.<\/p>\n

The predominant share of the plant debris in fertile soil is thus rapidly processed by micro-organisms, e.g. bacteria, leading to more bacteria and, in turn, also to more cell fragments<\/strong>. This then results in more organic material in the soil. \u00abEven though the greatest part of the organic carbon in the eco-systems is definitively produced primarily by plants, we were able to show that a large part of the organic material is actually composed of residues of bacteria and fungi<\/strong>. This underscores the importance of bacteria as organisms in all types of soil<\/strong>,\u00bb summarises Matthias K\u00e4stner. Furthermore, they are important for the global climate<\/strong>: The degradation of these organic material results, in mineralisation products and the greenhouse gas carbon dioxide (CO2<\/sub>). According to estimates from Great Britain the amount of CO2<\/sub> escaping annually to the atmosphere due to the degradation of organic material in the soils of England and Wales is in the order of magnitude by which greenhouse gas emissions are annually reduced there. This means that no rigorous progress in climate protection may be accomplished without first protecting the soil<\/strong>.<\/p>\n

\u00a0Story Source<\/span>: <\/strong>The above story is reprinted from materials<\/a> provided by Helmholtz Centre For Environmental Research – UFZ<\/strong><\/a>. Note: Materials may be edited for content and length. For further information, please contact the source cited above.<\/em><\/p>\n

\u00a0<\/strong>Journal References<\/strong><\/span>: (1) Christian Schurig, Rienk H. Smittenberg, Juergen Berger, Fabio Kraft, Susanne K. Woche, Marc-O. Goebel, Hermann J. Heipieper, Anja Miltner, Matthias Kaestner. Microbial cell-envelope fragments and the formation of soil organic matter: a case study from a glacier forefield<\/strong>. Biogeochemistry<\/em>, 2012; DOI: 10.1007\/s10533-012-9791-3<\/a>; Anja Miltner, Petra Bombach, Burkhard Schmidt-Br\u00fccken, Matthias K\u00e4stner. SOM genesis: microbial biomass as a significant source<\/strong>. Biogeochemistry<\/em>, 2011; DOI: 10.1007\/s10533-011-9658-z<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

La nota de prensa que os ofrecemos hoy nos informa de la importancia de la materia org\u00e1nica de origen bacteriano en los suelos. as\u00ed como de\u00a0su papel en la estructura de los ecosistemas ed\u00e1ficos, fertilidad y secuestro de carbono atmosf\u00e9rico. Se trata de nuevas indagaciones que, en parte, cambian la percepci\u00f3n vigente, del rol desempe\u00f1ado por las sustancias h\u00famicas en los suelos. Toda novedad debe ser corroborada debidamente antes de incorporarse al corpus doctrinal de una disciplina, por lo que habr\u00e1 que esperar estudios posteriores con vistas a validar si se trata de \u201cciencia buena\u201d. Hasta la fecha los expertos\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":[596,608],"tags":[47111,47412,47415,47388,47413,47414,46734],"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\/143534"}],"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=143534"}],"version-history":[{"count":7,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/posts\/143534\/revisions"}],"predecessor-version":[{"id":144862,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/posts\/143534\/revisions\/144862"}],"wp:attachment":[{"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/media?parent=143534"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/categories?post=143534"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/tags?post=143534"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}