Gut bacteria are what we eat

I have been saying it... the Science is *beginning* to prove it...

"It's a fascinating story," said microbiologist Jeffrey Gordon of Washington University School of Medicine in St. Louis, who did not participate in the study. "It shows that there's a dimension to human evolution that's occurring at the level of our gut microbiome."

"This is an exciting development," agreed microbiologist Justin Sonnenburg of Stanford University School of Medicine, who also was not involved in the research. "I think we're at the tip of the iceberg here. Human diet is so diverse, I think that we're just getting an initial glimpse of what's likely to be really huge area of variation that differentiates populations of humans."

The human digestive tract harbors trillions of bacteria, many of which establish lifetime, symbiotic relationships with their hosts. The food we eat nourishes our gut flora, and those bacteria feed us with the products and byproducts of their own digestive activities. Consequently, the gut microbiome has evolved to encode a variety of digestive enzymes, for example, those that break down hard-to-digest polysaccharides in food plants, such as celery, broccoli, and other vegetables.

As a PhD student at the Station Biologique de Roscoff in France, biochemist and co-author on the Nature paper Jan-Hendrik Hehemann was interested in a different type of enzymes -- bacterial catalysts that break down polysaccharides in marine algae, which contain sulfates not found in typical food plants. Hehemann and his colleagues identified several genes that they suspected to code for those specialized enzymes in a recently sequenced marine bacteria genome and tested their activity on red algae extracts. Their results revealed that the enzymes encoded by two of the genes represent a whole new class of carbohydrate-digesting proteins, capable of degrading porphyrans -- a unique component of marine plant polysaccharides.

Mining the databases for other marine bacteria that might also contain these so-called porphyranases, Hehemann instead stumbled upon a gut bacterium found in human populations inhabiting Japan (but not North America). The similarities between the genomes of the two bacteria suggested that gut microbe had somehow obtained those genes directly from the marine species. "I was really blown away by this result," he recalled.

link...

http://www.the-scientist.com/blog/display/57272/

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