Tiny microbes beneath the sea floor may account for one-tenth of the Earths living biomass

July 22nd, 2008 - 12:37 pm ICT by ANI  

Washington, July 22 (ANI): A new research has determined that tiny microbes beneath the sea floor, distinct from life on the Earths surface, may account for one-tenth of the Earths living biomass.

Our first study, back in 2006, made some estimates that the cells could double every 100 to 2,000 years, said Jennifer F. Biddle, a postdoctoral associate at the University of North Carolina, Chapel Hill. Now we have the first comprehensive look at the genetic makeup of these microbes, she added.

The researchers looked at sediment samples from a variety of depths taken off the coast of Peru at Ocean Drilling Site 1229.

The Peruvian Margin is one of the most active surface waters in the world and lots of organic matter is continuously being deposited there, said Christopher H. House, associate professor of geoscience. We are interested in how the microbial world differs in the subsea floor from that in the surface waters, he added.

The researchers used a metagenomic approach to determine the types of microbes residing in the sediment 3 feet, 53 feet, 105 feet and 164 feet beneath the ocean floor.

The use of the metagenomics, where bulk samples of sediment are sequences without separation, allows recognition of unknown organisms and determination of the composition of the ecosystem.

The results show that this subsurface environment is the most unique environment yet studied metagenomic approach known today, said House. The world does look very different below the sediment surface, he added.

House noted that a small number of buried genetic fragments exist from the water above, but that a large portion of the microbes found are distinct and adapted to their dark and quiet world.

The researchers found that a large percentage of the microbes were Archaea, single-celled organisms that look like Bacteria but are different on the metabolic and genetic levels.

The percentage of Archaea increases with depth so that at 164 feet below the sea floor, perhaps 90 percent of the microbes are Archaea.

The total number of organisms decreases with depth, but there are lots of cells, perhaps as many as 1,600 million cells in each cubic inch.

These microbes influence the Earths long-term carbon cycle and also these microbes may be quite ancient, said Biddle.

If the rest of the world is like the Peruvian Margin, then at least one tenth and as much as a third of the Earths biomass could be these tiny microbes living in the mud. (ANI)

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