Importance of Microbes
The human body has 10-100 trillion microbes living on it, making it one giant super-organism. Since the first link between microbes and diseases was made, people have been advised to wash there hands. Scientists, however, have recently started to investigate more closely how the microbes that call the human body home affect our health. While some microbes cause disease, others are more beneficial, working with our bodies in many subtle ways.
As with the human body, microbes throughout the world play important roles in their ecosystems. In spite of being extremely small, the sheer number of microbes living on the planet have large effects on the cycling of nutrients and compounds, both essential for the survival of all organisms. To survive in so many types of habitats, microbes have evolved a great number of mechanisms to find energy, digest food and reproduce. Scientists use these skills in a number of ways, including agriculture, energy production, medicine and warfare.
Ten times as many microbes live on or inside your body as you have cells. For the most part, we live peacefully alongside these alien hitchhikers. In fact, many of these microbes are actually beneficial. The microbes living in our digestive system break down food and produce useful vitamins. The millions of microbes that coat our skin and insides form a protective barrier against more dangerous microbes. Without them, our bodies would be open to microbial attack.
In spite of the benefits, a relatively small number of microbes are harmful to humans. Many diseases and epidemics are caused by microbes: the plague during the Middle Ages, smallpox, AIDS, influenza, food poisoning and anthrax. These diseases result in severe illness, or even death. As scientists learn more about bacteria, fungi and viruses, they are better able to treat and prevent these diseases. Common treatments include antibiotics that kill bacteria and vaccines that help the body fight off viruses.
Microbes & Ecosystems
Microbes obtain energy from their environment. Like humans, many microbes do this by eating plant and animal material. A typical microbe buffet consists of waste from humans and other animals, dead plants and animals, and food scraps. Bacteria, fungi and algae all take part in decomposing — or breaking down — this waste material. Without them, the world would quickly be overrun with discarded food scraps, raw sewage and dead organisms.
Microbial decomposition releases nutrients into the environment that are needed by other organisms. Microbes are also involved in the cycling of many other important compounds in — and between — ecosystems, including oxygen, carbon and nitrogen. Many microbes use the energy of sunlight to convert carbon dioxide to oxygen, which we need to breathe. As they do this, they create new organic material — themselves — which are then eaten by other organisms. In this way, the cycling of nutrients and energy continues.
Microbes & Food and Agriculture
People have a long history of using microbes in agriculture and food production. A nineteenth century B.C. Sumerian tablet contains a recipe for making beer using the fermentation abilities of yeast. Microbes also play a part in the production of other foods, such as yogurt, cheese, wine, bread, vitamins, beans and chocolate.
In some cases, microbes function as they would in their original environment. For example, bacteria living around the roots of bean plants convert nitrogen from the air into a form that the plant can use, like fertilizer. People have also learned how to use the natural abilities of microbes to create new foods, as with making beer from grains.
Microbes are so efficient at what they do that scientists use them in many industrial applications. Decomposing microbes are active in wastewater treatment plants, composting facilities and landfills. They break down food scraps and waste materials into compost or fertilizer that can be used on gardens or in agriculture. Some industrial facilities capture methane gas that is produced during certain types of decomposition. The methane can then be used to make ethanol for cars or to generate electricity.
Many types of scientific research involve altering the DNA of microbes, or using their DNA to alter other organisms. By changing the DNA sequence of microbes, scientists can use them to create compounds that the microbes would not normally produce. This includes medical products like insulin, or sources of fuel. Microbes are also used to change the DNA sequence of other organisms, such as changing plants to become resistant to insects or viruses.
Microbes & Terrorism and Warfare
Using disease-causing microbes to cause harm is not a recent invention. Historical records show armies using infected corpses against their enemies as far back as the sixth century B.C. This included dumping them in wells to poison the water, or catapulting them into a city to cause an outbreak of disease. The colonization of the Americas included many incidents of Europeans using the smallpox virus against the native population. All of these events occurred even before scientists fully understood how microbes caused diseases.
In the twentieth century, scientists refined the technique of using microbes in warfare. This led to not only biological warfare, but also bioterrorism. During both world wars, Germany used microbial diseases against enemy soldiers, as well as prisoners of war. In response, the Allied countries developed their own biological weapons, using microbes such as anthrax, a type of bacteria. Various treaties have been signed by countries to limit the use biological weapons, although some countries continued their biological weapons programs into the twenty-first century.