are the microorganisms which have both the positive and negative impacts for us. They are beneficial for us because they are used in a number of industries like for producing dairy products like yogurt, cheese etc. They are also used in Leather industry for making leather. Bacterias are also economical beneficial organisms because Nitrogen fixing bacterias, increases the fertility of the soil by processing nitrogen in the soil. Bacteria are also important for our health because they are present in our body and are producing a vitamin type in our body. Moreover, bacteria are also used in manufacturing medicines like anti-bacterial medicines.
There are various harmful effects of bacteria as well. For example, bacteria in our body can cause gastrointestinal infections as a result of the ingestion of contaminated food. Such bacterias include Escherichia coli, Proteus or Klebsiella species. Bacteria can also make our food contaminated and they can cause many serious bacterial diseases. Moreover, if they are used in many food products industries
, then they can also spoil the food as well, which can cause huge losses.
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.
There are also now bacteria being added to foods such as yogurt, which is itself a probiotic (live bacteria) culture. These are expected to aid in immune responses and digestion as well as alleviate lactose intolerance. Both Yoplait and Breyers brands tout such "live and active cultures" of useful bacteria.
# Transform organic carbon to carbon dioxide (CO2)
# use up oxygen when sufficient carbon is available for growth
# transform nitrogen between oxidized (e.g., nitrate - NO3) and reduced (e.g., ammonium - NH4 or nitrogen gas - N2) forms
# transform iron between oxidized [Fe(III)] and reduced [Fe(II)] forms
# transform sulfur between oxidized (e.g., sulfate - SO4) and reduced (e.g., sulfide - H2S) forms
# produce methane
# degrade pesticides, fuels and other organic contaminants
# affect the distribution and solubility of some metals (e.g., arsenic, uranium, etc.)
* Certain bacteria act as pathogens and cause tetanus, typhoid fever, pneumonia, syphilis, cholera, food-borne illness and tuberculosis.
* Streptococcus bacteria may cause small infections like strep throat and some serious diseases like pneumonia. Certain streptococci may be fatal.
* Bacteria that usually live harmlessly in the body may cause infections when a person's resistance to disease is reduced in conditions such as AIDS (Acquired Immune Deficiency Syndrome).
* Not all stomach bacteria are beneficial, some of the stomach bacteria enter the body through the mouth, and they can survive in the acidic conditions in the stomach and can cause serious diseases and can be fatal.
* Campylobacter is a group of bacteria that can create illnesses in humans and is a common cause of food poisoning.
* Harmful bacteria in food cause botulism, which can cause paralysis or even death if even one millionth of the bacterium is ingested.
* Yersinia pestis or bubonic plague, is a rod-shaped type of bacterium which is well known for its harmful nature. Bacteria-carrying fleas found on animals such as rats and mice transmit the bacteria that are believed to have caused the deaths of millions of people in human history.