Monday, January 09, 2006


The current round of research into soil microbial life holds the door open onto insights that stagger the imagination.
Discoveries about vesicular arbuscular mycorrhizal fungi (VAM) and arbuscular mycorrhizal fungi (AMF) transformed our understanding of the contribution of soil fungi to soil function. Current research indicates that similarly monumental discoveries may await us.

Genome research and computational improvements demonstrate that the number and diversity of soil bacteria species far exceed the levels anticipated.

Bacteria make up the bulk of life on Earth and play a vital role in the lives of other organisms. But scientists have barely scraped the surface when it comes to identifying bacteria – 99% of species cannot be grown by standard techniques in the laboratory. ... Soil is ... a complex microbial environment containing thousands of distinct species – most of them bacteria – in just a half-gram sample.


More than one million distinct genomes occurred in the pristine soil, exceeding previous estimates by two orders of magnitude.

The distribution of this diversity is unequal in ways that may seem counter intuitive. The following was reported earlier today in What's New in Science and Technology .

Ironically, in the diversity of soil bacteria, the otherwise species-rich Amazon is a more like a desert, while the arid desert is a teeming microbial Amazon, researchers have found. Their first-ever continental-scale genetic survey of soil bacteria revealed that the primary factor that seems to govern the diversity of soil bacteria is soil pH. Thus, the acidic soils of topical forests harbor fewer bacterial species than the neutral soils of deserts.

The researchers said that, since soil bacteria play a fundamental role in a vast array of ecological processes, their survey constitutes an initial step in a new research pathway to understanding that role.

As exciting as these studies are, they are tentative and simplistic in comparison to the dynamic they reveal. These results are the product of capacity building needed before the real work can begin.

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