Here’s a new way to prove the maxim that we are what we eat: Take a peek into the teeming universe of bacteria that thrive in a Japanese person’s gut. Trillions of microbes in the gut help digest the foods we eat, and researchers have found that the “gut microbiomes” of Japanese people have adapted over the centuries to help digest seaweed–an integral part of sushi. Remarkably, they adapted by taking in genetic material found in that very sushi.

The new study, published in Nature, reveals that these gut bacteria engaged in a gene swap, grabbing algae-digesting genes from marine bacteria that live on red algae like nori, the seaweed used to wrap sushi. The marine bacteria traveled on the seaweed into human digestive systems, where the crucial genes were transferred to bacteria in the gut.

Scientists stumbled on this swap when they identified a new group of enzymes from the algae-chomping marine bacteria that help the microbes break down the unique carbohydrates in seaweed. When they searched for other organisms that had the same enzymes, they found one match that, oddly, came from a species of bacteria that lived in the gut of a Japanese volunteer. Further study revealed that this species of gut bacteria is seen only in Japanese individuals.

For an in-depth look at what the horizontal gene transfer means and how this could affect your sushi-chomping habits, turn to the new DISCOVER blog Not Exactly Rocket Science and Ed Yong’s illuminating post, “Gut bacteria in Japanese people borrowed sushi-digesting genes from ocean bacteria.”

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Image: Flickr/johndmelo

Sushi lovers, we’ve got some bad news. For a study that came out in PLoS One, researchers ordered sushi at restaurants across New York City and Denver, Colorado, and found that an alarming percentage wasn’t made from the fish it was advertised to be. More than half of the eateries weren’t completely clear and honest about the fish they offered, the study says. Some even mistakenly served up escolar, which can give people diarrhea and stomach problems.

Although their results were shocking, exposing sloppy sushi joints wasn’t their main goal. The scientists were trying to improve on a new species-identification technique, called DNA barcoding…. Their goal is to build a catalog of every fish species on earth so that anyone with a handheld DNA reader could definitively identify fish within minutes [Wired.com].

One reason researchers investigated sushi is that so much of it has been made from endangered species like the bluefin tuna. In the restaurants that lead scientist George Amato checked out, the device showed 25 percent of what was labeled as tuna on sushi menus was bluefin, Amato said. The device also has been used to identify the presence of endangered whales in Asian markets and fraud in the labeling of caviar and red snapper [UPI].

This study comes in the wake of an international ruling that reduces the quota for bluefin catch from 22,000 metric tons annually to 13,500 for 2010. But that isn’t enough for many environmentalists, nor for The New York Times editorial board, which this weekend called for the United States to list bluefin under the Convention on International Trade in Endangered Species. The law effectively bars commercial trade in any listed species, and has been helpful in protecting other animals like elephants and whales [The New York Times].

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Image: flickr / avixyz