— Taken together, the microbes living in you weigh a few pounds. And within our bodies we have more than 10,000 different species of microbes. That’s a lot of different life forms, all co-existing with each other and with us.
Those arresting facts got my attention when scientists from the government’s Human Microbiome Project recently announced some of their research findings. My friend Dr. Phil Mixter of the School of Molecular Biosciences at Washington State University helped this rock head digest the news of the research.
A lot of the microbes you are carrying around live in your guts, some live on your skin, others up your nose.
Carting around pounds worth of little “bugs” isn’t as bad as it may sound. Four out of five microbes are likely beneficial to us.
Interestingly, the study found that most people have low levels of some harmful types of bacteria in them, organisms that can cause certain infections.
That raises questions that motivate scientists who work in this area: what makes some people fall sick due to certain microbes while others carry them around but don’t get ill – and may even benefit from their presence?
Another fun fact made clear by recent studies is that the microbes in you and me are as different as our fingerprints. You’ve got more of one microbe in you than I do, but less of another. The total “zoo” of microbes we carry around within us varies according to diet and even where we live.
One way to change your internal zoo is to take antibiotics. They kill off a number of microbes. If you’re lucky, that will include any organisms making you ill, but you’ll also lose some of the “good” organisms that you harbor within you. The beneficial bacteria in your gut, for example, will likely take a direct hit.
“While broad-spectrum antibiotics are useful in treating certain infections, it’s also clear such treatment can disrupt our beneficial microbes,” Mixter said.
Another important point is that microbes are far from passive passengers, just riding around on us.
“They are metabolically active,” Dr. Phillip Tarr, one of the lead researchers who performed the study, said to the media. “We now have to reckon with them like we have to reckon with the ecosystem in a forest or a body of water.”
The microbes living on and in you vary a lot by what part of your body they call home. Your guts have one flourishing community of microbes, your nose another.
The recent study surveyed the microbes on specific locations in many individuals using DNA typing. Microbes are very diverse on all persons and carry literally millions of microbial genes -– many more than are in the genetic makeup of an individual. And some of the genes are useful to us: it looks like genes from bacteria in our intestines help lead to the digestion of certain fats and proteins. We couldn’t function well without them.
Let’s here it for our little internal zoos, hard at work within us each day.
Dr. E. Kirsten Peters was trained as a geologist at Princeton and Harvard. Her column is a service of the College of Agricultural, Human and Natural Resource Sciences at Washington State University.