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The Golden Age Of Microbiology :      The period from 1857-1914 (60 years), beginning with the work of Pasteur, there was an explosion of discoveries in microbiology. This period has approriately named the golden age of mocrobiology. During this period, rapid advances, spearheaded mainly by Pasteur and Robert Koch, led to the establishment of microbiology as science. Discoveries during these years included both the agent of many diseases and role of immunity in the prevention and cure of disease.      During this productive period, microbiologists studied the Chemical activities of microorganisms, improved the techniques for performing microscopy and culturing microorganisms.      Pasteur showed a causal relationship between microorganisms and disease. He discovered that a virulent bacteria could be used as a vaccine on fowl cholera.      Robert Koch proved that microorganisms causes disease. Lister introduced the use of disinfectants to clean surgical dressings in order to control infections in humans. The Birth Of Modern Chemotherapy : Dreams of "Magic Bullet"      After the relationship between microorganisms and disease was established, medical microbiologists next  focused on the search for substances that could destroy pathogenic microorganisms without damaging the infected animal or human. Treatment of disease by using chemical substances is called chemotherapy. The success of chemotherapy is based on the fact that some chemicals are more poisonous to microorganisms than to the host infected by microbes.      The chemotherapeutic agents prepared from chemicals in the laboratory are called synthetic drugs. Chemicals produced naturally by bacteria and fungi to act against other microorganisms are called antibiotics.      The first antibiotic was discovered by accident. Alexander Fleming, almost tossed out some culture plates that had been contaminated by mold. Fortunately, he took a second look at the curious pattern of growth on the contaminated plates. There was clear area around the mold where the bacterial culture had stopped growing. The mold was later identified as pencilium notatum and the mold's active inhibitor penicillin. Thus, Penicillin is an antibiotic produced by a fungus. Modern Development Of Microbiology :      The ground work laid during the Golden age of Microbiology provided the bases for several monumental achievements during the twentieth century.      New branches of microbiology were developed, including immunology and virology. Most recently, the development of a set of new methods called recombinant DNA technology has revolutionized research and practical applications in all areas of microbiology. DNA stands for deoxyribonucleic acid, a molecule that contains the genetic code (gene). Recombinant DNA And Biotechnology : (Genetic engineering)      Although natural recombination makes it possible for closely related organisms to exchange genes. The new technigues make it possible to transfer genes between completely unrelated species. There techniques are so powerful that the term recombinant DNA is now widely understood to mean any artificial manipulation of the genes, whether within a particular species or between different species.      A gene from a vertebrate animal, including a human, can be inserted into the DNA of a bacterium, or a gene from a virus into a yeast. In many cases, the recipient can then be made to express the gene, which may code for a commerially useful product. Thus bacteria with genes for human insulin for treating diabetes, and a vaccine for hepatitis B is being made by a yeast carrying a gene for part of the hepatitis virus (the yeast produces a viral protein).      New recombinant DNA techniques can also be used to make thousands of copies of the same DNA molecule, i.e. to amplify DNA, thus generating sufficient DNA for various kinds of analysis.

BACTERIA VIRUSES FUNGI