Causes of Microbes

Microbes are complex organisms that can be both helpful and harmful to human beings. While microbes such as Salmonella typhi, found in bad animal meats and dairy products, may be harmful for human health, the microbe Streptomyces is found in soil and chemically combines with other ingredients to create an antibiotic that treats infections. Each bacterium is a living being just like a human, growing and prospering in conditions conducive to its health, or dying in adverse conditions.

Bacteria

• Microbes are living beings that inhabited the earth before any other life form. There are different types of microbes, and each type may live alone or clustered together with other microbes, as single cells or made from a chain of many cells. Among these types, there are bacteria, viruses, algae, fungi and protozoa. Within these divisions are thousands of separate types with different shapes, genetic material and functions. Some are harmful to humans, some helpful and some simply coexist. Microbes may be self-sufficient or require inhabitation of another being, such as a human or other animal, to live.

Growth

• When speaking of microbial growth, scientists are really referring to cell division. Because cells are too small to see with the naked eye, it is nearly impossible to detect changes in the size of a single microbe. Instead, scientists who culture microbes can monitor cell division, documenting what type of environments allow the cell to divide and prosper, and what type of environments kill the microbe or stunt growth. For example, extreme heat or sanitizing solutions -- such as hand soap -- will kill certain microbes, but warm, moist environments may provide the same microbe with ideal conditions for cell division.

Death

• To think about how microbes die, consider harmful bacteria that enter the human body. The immune system is the body's natural defense against bacteria, as our cells attempt to attack, eliminate or at least stunt the growth of bacteria cells. When our immune system cannot complete the job, we take antibiotics. Different antibiotics work to kill harmful microbes in different ways. Some attack the cell wall of the bacteria, disrupting the destructive function made possible by that bacteria's genetic material. A bacteria, or any other microbe, will die off when an important part of its structure is attacked, blocked off or destroyed.

Disease

• Millions of microbes inhabit our bodies every day, in our armpits, in our saliva, in our mucus and on our scalps, among other places. When harmful microbes enter our bodies, however, it can result in temporary sickness or an infectious disease. Microbes that live on human bodies without negatively affecting health are in a symbiotic relationship with that body, meaning each being can coexist peacefully and even promote health and protection in the other being. Harmful microbes are those that must compete for resources with the cells of the human body. As the bacteria and human cells compete, sickness develops and symptoms such as fever, rash and headaches occur. If the body's immune system, antibiotics or other treatments fail, the microbe may defeat the cells of the body, causing death.