Who and what would we be without the trillions of microorganisms living in us and on us?
This illustration shows the body sites that will be sampled from volunteers for the Human Microbiome Project. Courtesy NIH Medical Arts and Printing
According to a growing body of new research investigating the human microbiome, who we are, biologically speaking, is much more diverse than we thought. The emerging findings indicate that our biological integrity and identity are intrinsically tied to the bacterial ecosystems, the communities living with us. Rather than an individual, separate body that is all “human,” the research indicates that we are more like a multi-organism ecosystem. “We need to start thinking of ourselves as super-organisms,” says Dr Julie Segre, senior investigator at the US National Institute of Health.
It now appears that these microbial communities are a fundamental part of who and what we are. “This is the second genome - the bacterial genomes as well as the human genomes, all of that is part of the true genetic content of a human.”
What is a Biome?
A biome is the total community of life occupying a major ecological zone or region, like a rain forest, desert, mountain range, fresh water marsh or a coral reef. A microbiome is a newer term, referring to ecological communities of microorganisms living in certain regions. The human microbiome is the collective genomes of all microorganisms present in or on the human body, from our skin to our lungs, from our mouth to the uro-genital tract. The biggest human microbiome ecosystem is in the gut.
Biologically, we live in a collective with microbial communities, trillions and trillions of them, without which there would be no cellular life. All species alive on this planet share in this common symbiotic relationship with microbial communities. Microbial organisms are nature’s master recyclers, like miniature chemical factories, changing one form of organic matter into another. At a very basic level, they break organic matter down to smaller molecular components, such as turning dead plants and animals into re-usable building blocks, which are then reassembled in different forms as needed by other plant and animal species. All plants and animals rely on the routine metabolic processes of microbial organisms to live.
Advances in Research
This digitally-colorized scanning electron micrograph (SEM) depicted a small grouping of Gram-negative Sebaldella termitidis bacteria. Recently, “the genome of ATCC 33386 S. termitidis was recently sequenced as part of the U.S. Department of Energy - Joint Genome Institute’s (DOE-JGI) Genomic Encyclopedia of Bacteria and Archaea (GEBA) project. Image CDC/Janice Haney Carr
The National Institutes Of Health launched the Human Microbiome Project in 2007 with the mission of studying these organisms and their role in human health. Powerful advances in gene sequencing technologies have opened up new possibilities, allowing researchers to study microbial communities as they exist in their natural habitats within the human ecosystem. This is significant because we can’t really get an accurate picture of their role by culturing them in a petri dish. The population, diversity and activities of these communities fluctuate with changes in our inner ecology, so to better understand them we must study them as they exist in nature, as part of the entire human ecosystem.
As the microbiome research progresses, the scientific thinking about the role of bacteria in human health is moving way past the simplistic view of bacteria as either pathologically dangerous or harmless squatters along for the ride. We’re learning how closely our bacterial communities are involved with the regulatory and information processing systems of our nervous system, endocrine and immune systems. There’s a continuous conversation, an ongoing non-stop stream of chemical signaling between our cells and systems and the bacterial communities living on us and in us. Our bodies are listening, talking and responding to the communication from these communities. It turns out we are dependent on them for a whole slew of vital activities; like breaking down fiber, assimilating vitamins, and keeping our skin supple and protected.
Our Health Depends on Ecosystems
Human Gut Microbe (Enterococcus faecalis) The bacterium, Enterococcus faecalis, which lives in the human gut, is just one type of microbe that will be studied as part of NIH's Human Microbiome Project. Courtesy United States Department of Agriculture
We are now discovering how much our own health depends on the health, diversity, and balance of these communities. Imbalanced bacterial communities are implicated in all kinds of health conditions, including: obesity, diabetes, heart disease, lung disease, various gastro-intestinal disorders and even Alzheimer’s.
The study of the human microbiome has become an international collaboration. As the research findings come in, an entire new paradigm of human health is emerging. The more we discover about our relationship with these microbial communities and their role in human health, the more it seems that we are a biological community living as a collective, an ecosystem of organisms. In this paradigm, health is seen as an expression of ecosystem diversity, resiliency and balance. Consider the implications. If who we are biologically is a collective ecosystem, what does that imply for us psychologically and culturally?
Resources and links:
Discover Magazine: The Ecosystem Inside
Seed Magazine: The Deep Symbiosis Between Bacteria And Their Human Hosts Is Forcing Scientists To Ask: Are We Organisms Or Living Ecosystems?
Wired Magazine: The Wired Atlas of the Human Ecosystem
NIH Microbiome Project: Impacts on Health
NIH News: NIH Launches Human Microbiome Project
The NIH Common Fund: Human Microbiome Project
International Human Microbiome Consortium
Videos:
The NIH Human Microbiome Project
Vincent Young MD PhD from The University of Michigan discuss the NIH program to catalog the bacterium that normally live with the human body.
Gut Bacteria and Health
(this is also a downloadable mpeg4)
Audio:
Radio Interview with Dr. Julie Segre, senior investigator at the US National Institute of Health
