Mapping Macrobes

| 20th August 2008
Mapmaking and conquest has a disturbingly close history. As indigenous people learned, the innocuous mapmaker may be followed by weapons, property claims and exploitation.

So too for the recent rash of science projects using mapping. The mapping of the human genome was accompanied by a massive patent grab on human genes. By mapping online social networks, internet marketers exploit new markets, while Big Pharma waits hungrily for new maps of the brain to offer opportunities to sell mood, attention, sleep and memory drugs.

The Human Microbiome Project is a $115 million attempt to map genetically all the microbes (bacteria, yeast and other single-celled critters) that inhabit the human body. Initial studies suggest our skin is crawling with a trillion microbes. Our mouths sustain 700 different microspecies, 10 billion in every gob of spit. The human gut harbours 100 trillion micro-organisms. Microbes outnumber the cells of the body 10 to one.

What interests microbial mapmakers is that our resident microbes (our so-called ‘microbiome’) are not getting a free ride. The body employs microbes to break down food, ward off invaders and boost immunity. Researchers estimate 10 per cent of all the body’s chemicals are produced by microbes. Over history, microbes have swapped genes with the body and become inheritable mitochondria in its cells. Most worrying are suggestions that our microbial passengers help control our behaviour. One tiny parasite, Toxoplasma gondii, secretes chemicals that make mice fatally attracted to cats. It is controversially suggested the same bug also brings on human behaviour patterns such as promiscuity and violence.

Waiting in the wings are a handful of business plans to exploit knowledge of the human microbiome, from the probiotic yoghurt industry to biotech companies like Florida-based Oragenics, which is going through FDA approval for genetically engineered bacteria it claims will out-compete the species that cause tooth decay. It calls this approach ‘replacement therapy’ – replacing an existing microbiome with a new engineered one. Leading researchers in the human microbiome project have filed a patent on a method they claim could make fat people skinny (or vice versa) by replacing the energy-efficient microbes resident in obese people with the more sluggish microbes found in leaner folks.

Most significant is the emerging evidence that everyone has a different set of microbes – a microbiomic fingerprint. Pharmaceutical companies and food companies would like to sell you drugs and foods perfectly matched to your own personal bacteria. Forensics experts would like to find out where you have been and with whom by examining the microbes you breathed in or left behind.

Most intriguing, because microbial populations in the air may differ by geographical location, a breath sample may reveal whether you have been taking the mountain air in Northern California or Northern Afghanistan. Instead, mapping and controlling microbes may become interchangeable with tools mapping and controlling human populations.

This article first appeared in the Ecologist August 2008


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