A Typical Human Gut Contains About 100 Trillion Bacterial Cells
Today I found out the human gut contains about 100 trillion bacterial cells, about 10 times as many cells as make up the human body. In other news, today I found out that the human body is made up of about 10 trillion cells. 
The human gut is basically sterile until you are born. For the first year of your life, the cultures of bacteria and other microbes in your gut fluctuate wildly and begin settling down around the time you start weaning.
Recently, a study was conducted, published in the journal, Nature, with scientists from Germany, Brussells, Beijing, Denmark, Spain, France and the UK all combined in a massive cataloging of microbes in the human gut, most of which are bacteria. The research, led by Professor Jun Wang from Beijing Genomics Institute-Shenzhen, also found that there are about 160 unique species of microbes in the average person’s gut, also most of which are bacteria.
In this study, these scientists for the first time managed to decode all the microbial genes found in the human gut. Given that we are so incredibly dependent on these bacteria for a variety of health reasons, this research could very quickly lead to significant advancements in various medical fields, including how we treat and recognize a variety of ailments. Currently, next to nothing is known about the majority of these bacteria living in a symbiotic relationship with us and yet they clearly have a huge effect on our health and well being.
As Dr Jerome Raes, a researcher who was part of the study said, “We have no clue as to how the gut works because this is a very complex ecosystem. We really don’t know how that ecosystem works even though it is crucial for our well being. We don’t know how food is digested and which species do what.”
“We’ve basically sequenced all of their (the subjects) genomes at once. It was a huge effort because it’s basically the biggest sequencing exercise anyone has done so far – it’s about 200 times the sequencing effort of the human genome project,” he said.
These bacteria help us digest food, provide vitamins, and protect us from invading pathogens. When something happens to these cultures, it is known that it can lead to such problems as Crohn’s disease, Ulcerative colitis, and even has been linked to obesity. With Crohn’s and Ulcerative colitis scientists have now already been able to tell which people have these medical problems based on what cultures of bacteria are in their gut.
In this study the team analyzed fecal matter from 124 Europeans. Surprisingly, and going against less detailed research in the past, using new methods to catalog the entire spectrum of bacteria in our gut, the researchers discovered that despite the diversity of subjects, they shared more or less the same types of bacteria in their guts. They also found an amazing number of previously unknown microbes.
“A lot of things we found were new… whenever you go fishing for microbial diversity you find thousands of novel species because the microbial world is vastly uncharted,” Dr Raes said.
“In the future, we should be able to modify the (microbial) flora to optimize health and well being,” he said.
“This also opens up the possibility of prevention through diet, and treatments tailored a person’s genetic and microbial profile.”
Bonus Factoids:
- Of all the genes in our gut, it turns out over 99% of them are bacterial.
- Over 1000 prevalent species were discovered with each person having about 160 species present in their guts and the vast majority of them being unknown in terms of what they do or what effects they have on us. Of these 1,000 species, they found over 3.3 million distinct genes spread across those species.
- Bacterial densities in a human’s colon are the highest recorded for any known ecosystem.
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