La biodiversidad microbiana del suelo es fundamental para la descontaminación de los productos agroquímicos y aguas residuales

Como es bien sabido, el suelo es un ecosistema complejo que alberga la mayor biodiversidad de organismos procariotas en la Tierra. Secuenciación genómica de las microbiota de algunos suelos. Fuente PLosOne

Las practicas inherentes a la agricultura industrial se encuentran causando estragos en las comunidades microbianas del suelo, tanto a nivel cualitativo como cuantitativo. Entre otras razones cabe señalar que los agroquímicos y las aguas residuales no depuradas utilizadas para el riesgo se encuentran cargadas de toxinas, como lo son los metales pesados entre otras  (por ejemplo, cadmio, zinc y cobre). Los resultados de la investigación que os mostramos hoy  constatan que la aplicación de estos productos reduce la biodiversidad de los organismos del suelo. Conforme a los autores, basta tan solo una pérdida del 5% para que el medio edáfico sea incapaz de eliminar este tipo de tóxicos, que de este modo se acumulan en suelos, contaminando de paso las aguas superficiales y subterráneas. En consecuencia los autores proponen realizar test que de cuenta de la diversidad de grupos funcionales con vistas a monitorizar el estado de las comunidades microbianas, así como su potencial con vistas a realizar sus servicios ecosistémicos. Si en el propio ser humano, sus microbiomas, son vitales para la supervivencia de cada individuo, lo mismo podemos aseverar  respecto al medio edáfico. Se trata de la enésima constatación, de que en aras de una mayor producción, la agronomía actual proporciona comida y veneno en el mismo pack. Dejando de paso ricas toxinitas que dañan toda la biosfera. Cada vez que ingiera nutrimentos, como decía un antiguo amigo mío, piense que a su vez también esconden regalos envenenados Como en los roscones de Reyes, aquí en España). ¿Cuánto tiempo será necesario para que nuestras autoridades entiendan que por mucho que se invierta en otros ámbitos, como la salud, el mejor remedio es la prevención? ¿Y qué mejor prevención que investigar en otros modelos agro-productivos sustentables que nos ofrezcan alimentos saludables y no contaminados?.       

Abajo os dejo la nota de prensa de ScienceDaily, así como el resumen del artículo original en Suajili, bien claros e ilustrativos en esta ocasión.

Juan José Ibáñez

Loss of biodiversity limits toxin degradation

Date: January 16, 2014; Source: Wiley

Summary: You might not think of microbes when you consider biodiversity, but it turns out that even a moderate loss of less than 5 percent of soil microbes may compromise some key ecosystem functions and could lead to lower degradation of toxins in the environment.

You might not think of microbes when you consider biodiversity, but it turns out that even a moderate loss of less than 5% of soil microbes may compromise some key ecosystem functions and could lead to lower degradation of toxins in the environment.

Research published today in the SfAM journal, Environmental Microbiology, reports that without a rich diversity of soil bacteria, specialized functions such as the removal of pesticide residues are not as effective.

Dr Brajesh Singh of the University of Western Sydney led the work, he said «If the ability of the ecosystem to remove toxins from the environment is reduced, there will be higher toxicity risks in the environment and for non-target organisms, including humans, from agricultural chemicals. It is likely that these contaminants will remain at higher levels in surface and underground water, as well. It is vital to gain a better understanding of the extent to which soil bacteria are involved in the removal of contaminants.»

The reasons for, and extent of, the decline in microbial diversity in agricultural soils is likely to be complex. The team has looked specifically at long-term heavy metal pollution where metals such as cadmium, zinc, and copper build up in the environment, usually as a result of industrial use. Another source is from digested sewage sludge, which is spread in agriculture fields to supply nutrients to crops and improve soil fertility; the sludge has historically contained some heavy metals, which can become concentrated in the soil.

Although the concentration of heavy metal used this study was higher than the current EU limit, this study has confirmed that long-term exposure to such contaminants does reduce the diversity of bacteria in the soil.

With the global population set to reach nine billion by 2050, we face a challenge to feed an extra two billion mouths using the same resources that we have at present. Crop losses to pests and disease account for a large percentage of under-production and so giving up pesticides will be difficult. Similarly, the use of sludge as a fertilizer is likely to become more prevalent. Research like this allows us to understand better how to use important agrichemicals and waste products in a sustainable way and so will contribute to future food and environmental security.

Story Source: The above story is based on materials provided by Wiley. Note: Materials may be edited for content and length.

Journal Reference: Brajesh K. Singh, Christopher Quince, Catriona A. Macdonald, Amit Khachane, Nadine Thomas, Waleed Abu Al-Soud, Søren J. Sørensen, Zhili He, Duncan White, Alex Sinclair, Bill Crooks, Jizhong Zhou, Colin D. Campbell. Loss of microbial diversity in soils is coincident with reductions in some specialized functions. Environmental Microbiology, 2014; DOI: 10.1111/1462-2920.12353

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Wiley. «Loss of biodiversity limits toxin degradation.» ScienceDaily. ScienceDaily, 16 January 2014. <www.sciencedaily.com/releases/2014/01/140116113313

Related Articles: Biodiversity hotspot, Deforestation, Biodiversity, Organic farming, Sustainable land management, Soil life

Resumen del Artículo Original

Loss of microbial diversity in soils is coincident with reductions in some specialized functions

Loss of microbial diversity is considered a major threat because of its importance for ecosystem functions, but there is a lack of conclusive evidence that diversity itself is reduced under anthropogenic stress, and about the consequences of diversity loss. Heavy metals are one of the largest, widespread pollutant types globally, and these represent a significant environmental stressor for terrestrial microbial communities. Using combined metagenomics and functional assays, we show that the compositional and functional response of microbial communities to long-term heavy metal stress results in a significant loss of diversity. Our results indicate that even at a moderate loss of diversity, some key specialized functions (carried out by specific groups) may be compromised. Together with previous work, our data suggest disproportionate impact of contamination on microbes that carry out specialized, but essential, ecosystem functions. Based on these findings, we propose a conceptual framework to explicitly consider diversity of functions and microbial functional groups to test the relationship between biodiversity and soil functions.