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Microbiology, Application and Scope

Microbiology is a specialized area of biology that deals with microscopic organisms that are collectively referred to as microorganisms or microbes. There are several major groups of microorganisms. They are bacteria, algae, protozoa, helminths, fungi and viruses, which are noncellular, parasitic, protein coated genetic elements, dependent on their infected host.
The nature of microorganisms makes them both very easy and very difficult to study—easy because they reproduce so rapidly and we can quickly grow large populations in the laboratory and difficult because we can’t see them directly. We rely on a variety of indirect means of analyzing them in addition to using microscopes. Microbiology is one of the largest and most complexes
Microorganisms clearly have monumental importance to the earth’s operation. It is this very same diversity and versatility that also makes them excellent candidates for solving human problems. By accident or choice, humans have been using microorganisms for thousands of years to improve life and even to shape civilizations. Baker’s and brewer’s yeast, types of single-celled fungi, cause bread to rise and ferment sugar into alcohol to make wine and beers. Other fungi are used to make special cheeses such as Roquefort or Camembert. These and other “home” uses of microbes have been in use for thousands of years. For example, historical records show that households in ancient Egypt kept moldy loaves of bread to apply directly to wounds and lesions. When humans manipulate microorganisms to make products in an industrial setting, it is called biotechnology. For example, some specialized bacteria have unique capacities to mine precious metals or to clean up human-created contamination.
Genetic engineering is an area of biotechnology that manipulates the genetics of microbes, plants, and animals for the purpose of creating new products and genetically modified organisms (GMOs). One powerful technique for designing GMOs is termed recombinant DNA technology. This technology makes it possible to transfer genetic material from one organism to another and to deliberately alter DNA. Bacteria and fungi were some of the first organisms to be genetically engineered. This was possible because they are single-celled organisms and they are so adaptable to changes in their genetic makeup. Recombinant DNA technology has unlimited potential in terms of medical, industrial, and agricultural uses. Microbes can be engineered to synthesize desirable products such as drugs, hormones, and enzymesAmong the genetically unique organisms that have been designed by bioengineers are bacteria that mass produces antibiotic-like substances, yeasts that produce human insulin, pigs that produce human hemoglobin, and plants that contain natural pesticides or fruits that do not ripen too rapidly. The techniques also pave the way for characterizing human genetic material and diseases.
Another way of tapping into the unlimited potential of microorganisms is the science of bioremediation. This process involves the introduction of microbes into the environment to restore stability or to clean up toxic pollutants. Microbes have a surprising capacity to break down chemicals that would be harmful to other organisms. This includes even man-made chemicals that scientists have developed and for which there are no natural counterparts. Agencies and companies have developed microbes to handle oil spills and detoxify sites contaminated with heavy metals, pesticides, and other chemical wastes. The solid waste disposal industry is interested in developing methods for degrading the tons of garbage in landfills, especially human-made plastics and paper products. One form of bioremediation that has been in use for some time is the treatment of water and sewage. Because clean freshwater supplies are dwindling worldwide, it will become even more important to find ways to reclaim polluted water.
In addition to the crucial roles that microorganisms play in maintaining all life on earth, they also have made life more comfortable for humans over the centuries. Biotechnology is the application of biology to solve practical problems and produce useful products economically.
Food Production
By taking advantage of what microorganisms do naturally, Egyptian bakers as early as 2100 B.C. used yeast to make bread. Today, bakeries use essentially the same technology. The excavation of early tombs in Egypt revealed that by 1500 B.C., Egyptians employed a highly complex procedure for fermenting cereal grains to produce beer. Today, brewers use the same fundamental techniques to make beer and other fermented drinks. Virtually every human culture that has domesticated milk producing animals such as cows and goats also has developed the technology to ferment milk to produce foods such as yogurt, cheeses, and buttermilk. Today, the bacteria added to some fermented milk products are being touted by nutritionists as protecting against intestinal infections and bowel cancer, the field of probiotics.
The use of living organisms to degrade environmental pollutants is termed bioremediation. Bacteria are being used to destroy such dangerous chemical pollutants as polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT), and trichloroethylene, a highly toxic solvent used in dry cleaning. All three organic compounds and much more have been detected in soil and water. Bacteria are also being used to degrade oil, assist in the cleanup of oil spills, and treat radioactive wastes. A bacterium was discovered recently that can live on trinitrotoluene (TNT). Useful Products from Bacteria Bacteria can synthesize a wide variety of different products in the course of their metabolism. Many of these products have great commercial value. Although these same products can be synthesized in factories, bacteria often can do it faster and cheaper. For example, different bacteria produce:

  • Cellulose used in stereo headsets
  • Hydroxybutyric acid used in the manufacture of disposable diapers and plastics
  • Ethanol, which is added to gasoline to make it burn cleaner
  • Chemicals poisonous to insects
  • Antibiotics used in the treatment of disease
  • Amino acids, which are used as dietary supplements
Genetic Engineering
It is now possible to introduce genes from one organism into a related or an unrelated organism and confer new properties on that organism. This is the process of genetic engineering. Genetically engineered microorganisms often appear in the popular press because they are being used to solve many problems associated with an industrial society. Genetic engineering has expanded the power of biotechnology enormously. Here are examples of the roles that microorganisms play in this new biotechnology:
Microorganisms can be genetically engineered to produce a variety of medically important products. These include interferon, insulin, human growth hormone, blood clotting factors, and enzymes that dissolve blood clots.
Microorganisms are being modified so that they will produce vaccines against rabies, gonorrhea, herpes, leprosy, malaria, and hepatitis.
A bacterium can be used to genetically engineer plants so they become resistant to insect attacks and viral diseases, and produce large amounts of b-carotene.
A bacterium can be used to transfer antibody-eliciting genes into bananas which then confer resistance to certain diarrheal diseases.
Viruses are being studied as a means of delivering genes into humans to correct conditions such as cystic fibrosis, heart disease, and cancer. This is the process of gene therapy.
These examples represent only a few of the ways that microorganisms and viruses are being used to promote human welfare. In the past, microorganisms were considered only as dangerous organisms because they caused disease. The current and future use of microorganisms to increase the quality of human life, however, will receive increasing attention in scientific laboratories.
The DNA in bacteria carries all of the information that gives the organism its unique characteristics and the ability to carry out the activities that are essential to life on earth. To fully understand the basis for their remarkable diversity and what makes them tick, we need to sequence their DNA and thereby reveal this storehouse of information. This is the science of genomics. The DNA of about 100 different bacteria has now been sequenced, revealing the innermost secrets of these organisms. Scientists are now better able to understand how bacteria can live in widely diverse environments and their relationships to other organisms. This will allow scientists to improve organisms’ usefulness in biotechnology.
Medical Microbiology
In addition to the important roles that microorganisms play in our daily lives, some also play a sinister role. For example, more Americans died of influenza in 1918–1919 than were killed in World War I, World War II, the Korean War, and the Vietnam War combined. Modern sanitation, vaccination, and effective antibiotic treatments have reduced the incidence of some of the worst diseases, such as smallpox, bubonic plague, and influenza, to a small fraction of their former numbers. Another disease, acquired immunodeficiency syndrome (AIDS), however, has risen as a modern-day plague.
of the biological sciences because it includes many diverse biological disciplines. Microbiologists study every aspect of microbes—their cell structure and function, their growth and physiology, their genetics, their taxonomy and evolutionary history, and their interactions with the living and nonliving environment. Studies in Microbiology have led to greater understanding of many general biological principles.

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