What are Harmful and useful bacterias to human?

Answer 1

In the digestive tract are bacteria, the most famous of which is Lactobacillus acidopholus, which aid in digestion, compete with possibly virulent bacteria that are inhaled on a daily basis, synthesize vitamins, convert dietary fiber, and degrade toxins. There are more bacteria in the large intestine than there are cells in the human body. The bacteria also aid in developing a vigorous immune response; more than half of the body's immune tissue is located in the lining of the small intestine. All of the digestive tract bacteria are discharged from the body daily and renewed without causing disease. Antibiotics actually end up depleting the intestinal flora leaving a person susceptible to other infections. Staphylococcus epidermidis and P. acnes are two bacterial species that are naturally present on the skin; Streptococcus mutans is present in the mouth. These bacteria species can cause infection, acne, or dental plaques if not kept in check, but also compete out more virulent species of bacteria. Eliminating these colonizing species altogether would leave a person vulnerable to more severe infections.

It seems likely, however, that most people know bacteria best because of the diseases they cause. Some of these diseases are produced when bacteria attack directly the tissues in a plant or animal. For example, fruits and vegetables that become discolored as they are growing may be under attack by bacteria. Bacteria also attack organisms by releasing chemicals that are poisonous to plants and animals. Such poisons are known as toxins. A familiar toxin-producing bacterium is Clostridium tetani, responsible for the disease known as tetanus. Tetanus is a condition in which one's muscles are paralyzed, explaining its common name of lockjaw. A related bacterium, Clostridium botulinum, releases a toxin that causes the most severe form of food poisoning, botulism. Some forms of dangerous bacteria live on the human skin, but cause no harm unless they are able to enter the blood stream through a break in the skin. Among these bacteria is Staphylococcus, responsible for the potentially fatal Toxic shock syndrome. And although E. coli is helpful within the digestive system, if it is ingested and enters the bloodstream it causes severe cramping, diarrhea, and possibly even death. Most forms of food preservation, such as freezing and drying, are designed to kill or inactivate bacteria that would otherwise damage food or cause disease. One of the most common methods of destroying bacteria in foods is pasteurization. Pasteurization is the process of heating a food product to a particular temperature for some given period of time. The temperature and time are selected to be sure that all bacteria in the food are killed by the process. The pasteurization of milk has made it possible to insure safe supplies of one of the most popular of all human foods. http://www.scienceclarified.com/As-Bi/Bacteria.html

Answer 2

Some harmful bacteria to humans include Escherichia coli (E. coli), Streptococcus pneumoniae, and Staphylococcus aureus. Useful bacteria to humans include probiotics such as Lactobacillus and Bifidobacterium, which aid in digestion and overall gut health.