[permaculture] BBC NEWS | Science/Nature | Thousands of microbes in one gulp

Lawrence F. London, Jr. lfl at intrex.net
Mon Jul 31 18:26:29 EDT 2006

BBC NEWS | Science/Nature | Thousands of microbes in one gulp
Last Updated: Monday, 31 July 2006, 21:36 GMT 22:36 UK
Thousands of microbes in one gulp
Filamentous bacteria (Patterson/Amaral-Zettler/Edgcomb/micro*scope)
Diversity may be 10 to 100 times more than expected
One litre of seawater can contain more than 20,000 different types of bacteria, scientists have found.

The extraordinary number has been established by an international project attempting to catalogue all ocean life.

It suggests microbial biodiversity is much greater than previously thought, say Mitchell Sogin and colleagues.

Their research, published in the journal Proceedings of the National Academy of Sciences, is part of the Census of 
Marine Life (CoML).

It was undertaken using a new technique that allows for the rapid identification of distinct organisms by probing just 
small snippets of DNA.

It really points to our lack of knowledge and how much more there is to learn
Dr Mitchell Sogin, MBL
"Microbes constitute the vast majority of marine biomass and are the primary engines of Earth's biosphere," said Dr 
Sogin, from the Marine Biological Laboratory's (MBL) Josephine Bay Paul Center for Comparative and Molecular Biology and 
Evolution, located in Woods Hole, Massachusetts, US.

Density range

In the PNAS study, microbes were fished up from eight sites in the Atlantic and Pacific Oceans at depths of 550-4,100m 

The locations included extreme environments, both hot and cold, such as the North Atlantic and a hydrothermal vent 
located on an underwater Pacific volcano off the coast of Oregon.

The scientists expected to find about 2,000 species per litre of seawater. They were shocked to discover 10 times more 

"These observations blow away all previous estimates of bacterial diversity in the ocean," said Dr Sogin. "The number of 
different kinds of bacteria in the oceans could eclipse five to 10 million."

He told the BBC News website: "It really points to our lack of knowledge and how much more there is to learn."

The powerful new identification technique used by the microbiologists is called "454 tag sequencing".

It enabled the team to identify thousands of unusual types of microbes, some of which were present only in small 
numbers. They could easily have been overlooked by previous studies.

'Rare biosphere'

"Peering through a laboratory microscope into a drop of seawater is like looking at the stars on a clear night," said 
Victor Gallardo, vice chair of the CoML.

"The 454 tag sequencing strategy increases resolution like the Hubble Telescope. We can see marine microbial diversity 
to which we were blind before." A "rare biosphere" is how the scientists described these low-abundance background 

Cyanobacteria (Murray/Hoppenrath/Larsen/Patterson/micro*scope)
The project will extend its sampling of ocean waters
These unusual microorganisms are thought to contribute to an enormous range of novel genetic diversity in the ocean.

The researchers think that they might serve as a gene pool to preserve genetic innovations.

If environmental changes wiped out a dominant species, the low-abundance ones with a more suitable genetic makeup would 
be ready to take over.

"We know there will be major ecological changes on our planet. The microbial world has to survive the changes and one 
way is to have a lot of novelty in your genome so that you can cope with different environmental conditions," explained 
Dr Sogin.

Global reach

The census keeps a record of the distribution and numbers of the microbes. Scientists can then trace how the organisms 
adapt to changes and also, in the long run, understand what evolutionary driving forces might be at play.

"These rare, ancient organisms are likely to prove a key part of nature's history and strategy," explained Dr Gallardo.

Human beings are dependent on microbes for continued survival.

"The major photosynthesis in the ocean is carried by the microbial life forms, and that is the major input in terms of 
capture of energy from the Sun," explained Dr Sogin. "The microbes are a major input into climate parameters."

The project will scale up to 1,200 marine sites, including different conditions such as surface waters, waters near 
methane emissions from the sea floor, and deep-sea sediments.

The study forms part of the International Census of Marine Microbes (ICoMM), a component of the Census of Marine Life, a 
10-year global initiative started in the year 2000.

The CoML now involves more than 1,700 researchers in over 70 countries in efforts to assess and explain the diversity, 
distribution, and abundance of life in the oceans - past, present, and future.

More information about the permaculture mailing list