An estimated 10 million species of bacteria live on the Earth. These, and other microbes, make up a large part of the planet’s living material. Microbes thrive on land, in the oceans and on human skin. They even survive in extreme places like near deep-sea vents. People often think of microbes as just causing diseases — such as fungal infections in plants or pneumonia in humans. In spite of their bad reputation, microbes also play important roles in Earth’s ecosystems. For example, bacteria living in the ocean produce half of the oxygen in the atmosphere. Without them, we couldn’t breathe.
Even before the invention of the microscope, people noticed the effects of microbes on human health. Microscopes and other tools, however, enabled people to study these unseen creatures directly. Early on, scientists simply observed microbes. Later they began to understand how microbes live, grow and cause disease. This knowledge enabled scientists to develop ways to fight and prevent diseases caused by microbes. Scientists can also use microbes for many other applications, such as creating better food and new sources of energy.
Microbes are extremely small, and can only be seen with a microscope. They are smaller than a human red blood cell. Millions of microbes can fit inside the eye of a needle. They are also very old. In fact, they are the oldest form of life on Earth. They roamed the Earth — in their own microscopic way — hundreds of millions of years before the dinosaurs. They live everywhere. Dig up the soil, and you will find countless microbes living there. Take a sample of air, and they are there as well. They even live inside our digestive systems.
The many species of microbes can be organized in several ways. Familiar categories include the bacteria, fungi, and viruses. There are even microscopic animals — such as dust mites — which resemble tiny insects. Microbes can also be split into two groups based upon whether they have a cell nucleus. This membrane-bound part of the cell encloses the genetic material. In addition, microbes can be classified by how they obtain and process their food. Or how they react to oxygen. Some microbes need oxygen to survive. Others — like the ones living inside our digestive system — are killed by oxygen.
Microbes are essential components of every ecosystem. They produce the oxygen that we need to live. They break down garbage and dead organisms. They produce nutrients that plants need to grow. They even help us digest our food. In addition to these natural activities, microbes are needed for making foods like bread, wine and beer. Scientists also use microbes for practical applications. Microbes at a sewer treatment plant help breakdown the waste. Microbes can also be used to change the genetic composition of plants and animals. This gives them new traits, such as resistance to pesticides.
Microbes are probably better known for the diseases that they cause. AIDS, tuberculosis, bacterial meningitis and the common cold are all caused by microbes. Greater understanding of how microbes live and function, though, has enabled scientists to prevent and treat diseases. Vaccines, antibiotics and other drugs are powerful tools for reducing illnesses caused by microbes. Not all discoveries, however, were planned. Penicillin, an antibiotic produced by a fungus, was discovered largely by accident. In spite of the many scientific discoveries, washing and proper sanitation are still important tools in preventing diseases caused by microbes.
The invention of the microscope in the late 1600’s sparked the science of microbiology — the study of microbes. Scientists that study microbes are called microbiologists. Early on, microbiology focused on observing the tiny organisms visible through the microscope lenses. Over time the techniques for collecting and growing microbes improved. Microbiologists then began to understand how microbes reproduce, develop and cause disease. While we now know that bacteria can cause diseases, scientists only started to prove this in the 19th century.
Since its early beginnings, microbiology has expanded beyond just the microbes that affect human health. Microbiologists now study the entire range of microbes. The branches of microbiology can be defined by the organisms being studied. Microbiology can also be divided along more broad areas. These include areas such as evolution, genetics and applied fields, like industrial microbiology.
Microbes are challenging organisms to study. You can’t see them with the naked eye, so microscopes are needed to observe them directly. The earliest observations of microbes were made with simple lenses. Microscopes were then built with a combination of lenses. This enabled scientists to see more details and smaller organisms. Other types of microscopes and techniques were later developed. These provided scientists with a greater understanding of the microscopic world.
Observing microbes is only one of the challenges faced by microbiologists. Only a small fraction of microbes can actually be grown in a laboratory. This means that countless species of microbes have yet to be identified. Scientists can, however, study the microbes that are difficult to grow using other methods, such as DNA sequencing. Microbiologists are also able to alter the genetic material inside a microbe. This changes how the microbe behaves and functions.
Microbiologists interact with microbes in many fascinating ways. This makes microbiology a career with endless possibilities. Some microbiologists study one particular type of microbe, such as bacteria or viruses. Others focus on how microbes interact with people, plants or livestock. Scientists may also develop practical applications of microbes. Using special techniques, they can alter the microbes so they produce medicines. Or use their natural abilities to create better laundry detergents. Microbiologists may spend their time working in a laboratory, out in the field or doing mostly administrative work.
The career paths for microbiologists vary. Colleges offer two-year technical programs, bachelors and master’s degrees, and doctoral programs. The degree and field of study determines the kinds of jobs that an individual can obtain. Students can also combine a degree in microbiology with another field, such as business or journalism. This opens up new career paths.