Bacteria: The Roles They Play for Healthy Humans

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Bacteria live in the soil and on plants, animals and humans. The prolific numbers of bacteria in the world, with an estimated 10,000 species in a single gram of soil and nearly 500 species in human mouth, mean that bacteria outnumber humans. They are tiny. In fact, they are so small they require a high-powered microscope to be seen.

It is important to understand bacteria and the roles they play, as they are important in the ongoing cycle of life and death. They exist in the air inhaled, on the surface of skin and in mucus membranes. Many antibacterial products have been developed, and these can be helpful, when in the presence individuals who are sick. An oveuse of antibacterial products, however, may be harmful.

Bacteria line the surface of mucus in the respiratory tract, the digestive system and the urinary system. Their mere presence inhibits the colonization of “bad” bacteria, or those that would be disease producing. The wide range of normal flora actually create a barrier to disease-producing bacteria, so overuse of antibacterial products can kill these good bacteria.


Proper digestion of food is essential for good health and abundant energy. In the hidden recesses of the digestive system, microorganisms are hard at work breaking down foods into substances that can be easily absorbed by the digestive mucosa. The abundance of bacteria in the digestive system helps to quickly breakdown foods, acting on proteins and carbohydrates to break them down to their smallest components.

In the absence of good bacteria, pathogenic organisms can begin to colonize in the intestines, resulting in conditions like Clostridium difficile infections, which lead to diarrhea. This is usually due to overuse of antibiotics.

The same occurs in nature, with the breakdown of dead animals and plant material. The cycle of nature allows for the continual replenishing of soil with nutrients to reproduce new plant life, which then feeds animal life.

Vitamin K Production

Vitamin K is found in many vegetables, particularly green, leafy vegetables. Intestinal bacteria play a role in the synthesis of vitamin K. In cases where antibiotics may have destroyed much of the normal flora of the intestinal tract, endogenous production of vitamin K will be decreased. The amount of vitamin K that can be gained through eating a healthy diet is substantial, so generally a deficiency of endogenous vitamin K does not affect the total amount of the vitamin in the body.

Bacteria and Chemical Reactions

In addition to maintaining a strong defense against bad bacteria and aiding the digestive system, good bacteria are involved in chemical conversions that need to occur in the body. Through the function of good bacteria, bilirubin is converted to urobilinogen and bile acids are altered, converted and transformed into usable products. The composition of homeostasis is, in part, attributed to bacteria and the roles they play.