Our vital Microbiome: bacteria cure diseases too!
Recently, normal bacteria from a human gut were transplanted into another person who was suffering from a terrible gastrointestinal disease, and the disease was eradicated! The NYT recently published an article noting this feat, and summarizing our current understanding of the human microbiome, as the microbial species that inhabit our body are collectively known.
There are perhaps ten times the number of bacterial cells in a human body than the number of cells comprising the human body itself, and they are found not just in the gut, but on the skin and various other places in the body. It is thought that there are many thousands of bacterial species that colonize in humans.
It has long been known that bacteria are necessary for normal human health. Exactly which bacteria are necessary, and what they contribute specifically to our health is still not well characterized, but the amount of knowledge of the microbiome is growing very rapidly. Microbes provide us with vitamins and other molecules required for life. Some break down complex plant molecules. Some manufacture antibiotics that, in cooperation with our immune system, destroys dangerous pathogens. Some provide signals during human development. Even our immune system is signaled by microbes to help control inflammation.
In 2007, the Human Microbiome Project was started to sequence the DNA of bacteria that colonize in human tissue. They are using shotgun approach similar to that used in the Human Genome Project, by chopping up the DNA of bacteria harvested from a part of the human body, and then puzzling the fragments back together. With the human genome, there was only one organism to consider, but in this situation, the fragmented DNA may have thousands of species represented; By using the genomes of already sequenced bacteria, researchers are able to determine which species the fragment belongs to.
This has reaped a serious harvest already; 178 microbiome genomes have already been determined. With the determination of the genome comes a determination of the actual genes, then the proteins the genes code for. This gives some ability to determine function, and from there, better understanding of the contribution a particular bacterium brings to the function of the human body. Many other microbiological and physiological methods must still be used along side these genetic methods to ferret out the functions these microbes perform.
The road here is still very long, but the increased visibility into the human microbiome will bring significant contributions to our understanding of how the human body operates along side its vital complement of bacteria.