Microorganisms (Greek: micro, small) are tiny living forms—so tiny that they
typically cannot be seen without magnification. Microorganisms (or sometimes known as
microbes) include several major categories of organisms: protozoa, microscopic algae,
fungi, bacteria, and viruses. Most are unicellular, although some like molds and many algae
are considered multicellular.
Microbes can be found in a wide range of natural environments from arid land to
fertile soil, from fresh water to hot springs, and even inside the human body. Our bodies
support thriving populations of bacteria. Some are beneficial (e.g. many intestinal bacteria),
some harmful (e.g. sexually transmitted disease bacteria) and others are commensals (gain
benefit from their host without being harmful).
Many factors have an effect on microbes’ survival such as nutrients, temperature,
pH, presence of oxygen and so on; these parameters in turn are the key point in establishing
the particular microbial population. For example, in the hot spring only the microbes that
can tolerate high temperature can be found, the so-called “thermophiles”. Besides,
symbiotic interactions especially among the microbes themselves also play a key role for
their existence.
In our mouth, carbohydrate, protein and fat from food particles accumulate along
the line between the edge of the gums and the teeth. Together with constant warmth and
moisture this creates an ideal environment for bacterial growth. Plaque is the name given
to the resulting mixture of organic materials and bacteria.
In this laboratory you will be surprised with the presence of the microbes in the air
and even in our body.