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[Michaelangelica]

SOIL MICROBOLOGY: A PRIMER

By Vern Grubinger
Vegetable and Berry Specialist
University of Vermont Extension

Although it may not be obvious, healthy soils are chock-full of living organisms. Some are visible to the naked eye, like earthworms, beetles, mites and springtails, but the majority of soil-dwellers are very, very small. They’re also very, very important to soil fertility.

Just a few grams of soil, less than a teaspoonful, may contain hundreds of millions to billions of microbes. Not only is the total number of microorganisms in fertile soil quite high, but together, they weigh a lot, too. Soil microbial biomass can range from several hundred to thousands of pounds per acre.

By far, the most numerous microbes in soil are bacteria, which have just one cell. Also abundant are fungi, which produce long, slender strings of cells called filaments, or hyphae. The actinomycetes are in-between these two organisms. They are advanced bacteria that can form branches like fungi. It’s the actinomycetes that give soil its characteristic earthy smell. Fungi and actinomycetes are good at starting the decomposition of organic residues, working on materials that are tough to break down. Bacteria finish the job by eating the more digestible ingredients.

Many other microbes can be found in smaller numbers in soil, including algae, cyanobacteria (often called blue-green algae), and protozoa (one-celled organisms that decompose organic materials and also consume bacteria). Nematodes are microscopic roundworms; some of these are beneficial and some are plant parasites.

Soil Microbilogy: A Primer

May 30, 2006
Essential organism -- from peat bogs -- involved in global climate change is finally isolated for study
By Krishna Ramanujan

Among the unusual life forms found in peat bogs are carnivorous pitcher plants and methanogens, methane-producing single-celled organisms that live in oxygen-free environments. But efforts to take methanogens from acidic peat bogs and then isolate and culture them in the laboratory under peat bog conditions have been unsuccessful -- until now.

In a recent article in Nature Online, Cornell researchers published their methods for creating an acidic culture medium that isolated methanogens and allowed the organisms to thrive in a test tube. This will allow researchers to study methane-producing organisms and to better understand how they function in peat bogs and how they might respond to global climate change.

Indeed, methanogens play an important role in global climate because they are the largest natural sources of atmospheric methane -- a heat-trapping greenhouse gas 21 times more potent than carbon dioxide. Northern peat bogs hold one-third of the carbon fixed in the world's soils, the. . .

. . .
Even though methanogens dominate bogs, researchers have been unable to take them from the bog and then grow them in the laboratory. Braüer, Zinder and their colleagues used an antibiotic called rifampicin that killed off the bacteria in the sample but spared the methanogens. The methane-producers belong to a kingdom called Archaea, separate from bacteria and not bothered by most antibiotics.

Methanogens study