{"id":2052,"date":"2011-04-21T22:04:42","date_gmt":"2011-04-22T03:04:42","guid":{"rendered":"http:\/\/drcathiedunal.com\/blog\/?p=2052"},"modified":"2011-04-28T19:02:27","modified_gmt":"2011-04-29T00:02:27","slug":"gut-bacteria","status":"publish","type":"post","link":"http:\/\/drcathiedunal.com\/articles\/2011\/gut-bacteria\/","title":{"rendered":"Gut Bacteria: the New Blood Type"},"content":{"rendered":"

\"\"By Carl Zimmer, New York Times: <\/em>In the early 1900s, scientists discovered that each person belonged to one of four blood types. Now they have discovered a new way to classify humanity: by bacteria.<\/p>\n

Each human being is host to thousands of different species of microbes. Yet a group of scientists now report just\u00a0three distinct ecosystems<\/a> in the guts of people they have studied….The microbes alter the gut so that only certain species can follow them.<\/p>\n

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Whatever the cause of the different enterotypes, they may end up having discrete effects on people\u2019s health. Gut microbes aid in food digestion and synthesize vitamins, using enzymes our own cells cannot make.<\/p>\n

Dr. Bork and his colleagues have found that each of the types makes a unique balance of these enzymes. Enterotype 1 produces more enzymes for making vitamin B7 (also known as\u00a0biotin), for example, and Enterotype 2 more enzymes for\u00a0vitamin B1 (thiamine).<\/p>\n

The discovery of the blood types A, B, AB and O had a major effect on how doctors practice medicine. They could limit the chances that a patient\u2019s body would reject a blood transfusion by making sure the donated blood was of a matching type. The discovery of enterotypes could someday lead to medical applications of its own, but they would be far down the road.<\/p>\n

\u201cSome things are pretty obvious already,\u201d Dr. Bork said. Doctors might be able to tailor diets or drug prescriptions\u00a0to suit people\u2019s enterotypes, for example. \u00a0Or, he speculated, doctors might be able to use enterotypes to find alternatives to antibiotics, which are becoming increasingly ineffective. Instead of trying to wipe out disease-causing bacteria that have disrupted the ecological balance of the gut, they could try to provide reinforcements for the good bacteria. \u201cYou\u2019d try to restore the type you had before,\u201d he said.<\/p>\n

Dr. Bork notes that more testing is necessary. Researchers will need to search for enterotypes in people from African, Chinese and other ethnic origins. He also notes that so far, all the subjects come from industrial nations, and thus eat similar foods. \u201cThis is a shortcoming,\u201d he said. \u201cWe don\u2019t have remote villages.\u201d<\/p>\n

The discovery of enterotypes follows on years of work mapping the diversity of microbes in the human body \u2014 the human microbiome, as it is known. The difficulty of the task has been staggering. Each person shelters about 100 trillion microbes.<\/p>\n

(For comparison, the human body is made up of only around 10 trillion cells.) But scientists cannot rear a vast majority of these bacteria in their labs to identify them and learn their characteristics.<\/p>\n

As genetics\u00a0developed, scientists learned how to study the microbiome by analyzing its DNA. Scientists extracted DNA fragments from people\u2019s skin, saliva and stool. They learned how to recognize and discard human DNA, so that they were left with genes from the microbiome. They searched through the remaining DNA for all the variants of a specific gene and compared them with known species. In some cases, the variants proved to be from familiar bacteria, like E. coli. In other cases, the gene belonged to a species new to science.<\/p>\n

These studies offered glimpses of a diversity akin to a\u00a0rain forest\u2019s. Different regions of the body were home to different combinations of species. From one person to another, scientists found more tremendous variety. Many of the species that lived in one person\u2019s mouth, for example, were missing from another\u2019s.<\/p>\n

Scientists wondered if deeper studies would reveal a unity to human microbiomes. Over the past few years, researchers have identified the genomes \u2014 the complete catalog of genes \u2014 of hundreds of microbe species that live in humans. Now they can compare any gene they find with these reference genomes.<\/p>\n

They can identify the gene\u2019s function, and identify which genus of bacteria the microbe belongs to. And by tallying all the genes they find, the scientists can estimate how abundant each type of bacteria is.<\/p>\n

In the recent work, Dr. Bork and his team carried out an analysis of the gut microbes in 22 people from Denmark, France, Italy and Spain. Some of their subjects were healthy, while others were obese or suffered from intestinal disorders like\u00a0Crohn\u2019s disease. Dr. Bork and his colleagues searched for fragments of DNA corresponding to the genomes of 1,511 different species of bacteria. The researchers combined their results with previous studies of 13 Japanese individuals and 4 Americans.<\/p>\n

The scientists then searched for patterns. \u201cWe didn\u2019t have any hypothesis,\u201d Dr. Bork said. \u201cAnything that came out would be new.\u201d<\/p>\n

Still, Dr. Bork was startled by the result of the study: all the microbiomes fell neatly into three distinct groups.<\/p>\n

And, as Dr. Bork and his colleagues reported on Wednesday in the journal Nature, each of the three enterotypes was composed of a different balance of species. People with type 1, for example, had high levels of bacteria called Bacteroides. In type 2, on the other hand, Bacteroides were relatively rare, while the genus Prevotella was unusually common.<\/p>\n

\u201cYou can cut the data in lots of different ways, and you still get these three clusters,\u201d Dr. Bork said.<\/p>\n

Dr. Bork and his colleagues found confirmation of the three enterotypes when they turned to other microbiome surveys, and the groups continue to hold up now that they have expanded their own study to 400 people.<\/p>\n

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Article<\/a><\/p>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

By Carl Zimmer, New York Times: In the early 1900s, scientists discovered that each person belonged to one of four blood types. Now they have discovered a new way to classify humanity: by bacteria. Each human being is host to thousands of different species of microbes. Yet a group of scientists now report just\u00a0three distinct […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[271],"tags":[289,290,233,288,138,291],"_links":{"self":[{"href":"http:\/\/drcathiedunal.com\/articles\/wp-json\/wp\/v2\/posts\/2052"}],"collection":[{"href":"http:\/\/drcathiedunal.com\/articles\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/drcathiedunal.com\/articles\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/drcathiedunal.com\/articles\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/drcathiedunal.com\/articles\/wp-json\/wp\/v2\/comments?post=2052"}],"version-history":[{"count":18,"href":"http:\/\/drcathiedunal.com\/articles\/wp-json\/wp\/v2\/posts\/2052\/revisions"}],"predecessor-version":[{"id":2061,"href":"http:\/\/drcathiedunal.com\/articles\/wp-json\/wp\/v2\/posts\/2052\/revisions\/2061"}],"wp:attachment":[{"href":"http:\/\/drcathiedunal.com\/articles\/wp-json\/wp\/v2\/media?parent=2052"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/drcathiedunal.com\/articles\/wp-json\/wp\/v2\/categories?post=2052"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/drcathiedunal.com\/articles\/wp-json\/wp\/v2\/tags?post=2052"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}