Health diagnostics for the planet

April 02, 2013

A couple of weeks ago, my wife took our daughter to the doctor. After he had heard the symptoms my daughter had been experiencing, the doctor performed a rapid strep test. Within a few minutes he had diagnosed her with strep group A infection and prescribed antibiotics (she’s feeling much better now).

Rapid strep test.

A fast, easy, and painless health diagnostic exam, how cool is that? But according to the World Health Organization, health is “a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity.”

Is there a diagnostic exam that can actually measure all of this? Microbes may be the answer! Okay, so maybe that isn’t such a shocking statement. After all, germ theory, the discovery that some infectious diseases are caused by microorganisms, is going on 150 years old. PR-wise, humans and germs didn’t exactly get off on the right foot; bacteria generally have a bad reputation. Sure they’re nasty creatures responsible for countless deaths over the centuries and diseases ranging from tuberculosis to halitosis, but health isn’t just the “absence of disease”.

In the last few decades microbes have started to grow on us. Actually, they have always grown on us, and in us; but we are just now recognizing the benefits of having them around. Recent advances in technology have allowed us to explore the role of microbes in a number of different environments. Not only have we found that most bacteria aren’t harmful and that many are necessary for our health, but that our health is correlated with the community of microorganisms in and around us, known as the human microbiome. The correlation in some cases is so strong that the late Nobel Prize-winning Dr. Joshua Lederberg argued that the microbial community associated with us should be included as part of our genetic makeup. Others suggest that at the very least they should be considered a forgotten organ.

Depiction of the human body and bacteria that predominate; there are both tremendous similarities and differences among the bacterial species found at different sites.

There was even a recent paper that suggested that our skin is like an ecosystem and that different parts of our skin (scalp, hands, feet, etc.) are habitats for different groups of bacteria. In fact, the bacterial community on my heel is more similar to your heel’s community than it is to the bacterial community on my own hand. Similarly, the microbiome of a healthy person is quite different than that of someone who is unhealthy (even using the World Health Organization’s definition). The conclusion from many of these recent studies is that microorganisms can tell us a lot about the health of a person. But certainly there is more, after all humans (200,000-year history) are just the latest fad in the 3,500,000,000-year history of bacteria.

During their time on Earth, microbes have contributed to and maintained the conditions for life. Dr. James Lovelock hypothesized that living organisms and their interaction with inorganic material form a self-regulating system or a superorganism (Gaia). I know, this sounds a bit too ‘hippie-ish’ even for me, but let me run with it for a minute. If our Earth is a “super organismic system” (Dr. Lynn Margulis), can we assume that the status of microbial communities throughout this superorganism can tell us a lot about the health of our planet? We are finding that just like our skin, similar ecosystems on Earth have similar microbial communities. Different biomes, such as deserts, grasslands, and forests all have different microbial communities, but deserts all around the world (from Antarctica to the Southwest US) tend to have similar microbial communities.

Are microbes Gaia’s forgotten organ?

We at NEON are currently exploring how far we can take the concept of microbial diagnostics informing about ecosystem health. We're developing methods to examine all of the genes that are expressed by the microorganisms (metatranscriptomics) in the forest soils to explore differences in what the microbial communities are actually doing. We just got some data back from a preliminary study of different locations in Harvard Forest that have different vegetation types and levels of disturbance. Although analyses are still underway, we already have some promising results where we can distinguish red oak from successional shrubland and disturbed sites based solely on their microbiome. As NEON expands to multiple biomes throughout the US to monitor ecosystem health, we will be able to see how microbial communities change. NEON and other groups are working to learn more about Earth’s microbiome and how microbes regulate ecosystem health. It's exciting to think that NEON will have enough microbial data and information on the environment to actually map the interaction of microbial communities, environment, and plant diversity across an ecosystem.

Dialog content.