Golden age of microbiology:

•  Rapid advances in the science of microbiology were made between 1857 and 1914.

  Fermentation and Pasteurization:

•  Pasteur found that yeast ferments sugars to alcohols and that bacterium can oxidize the alcohol to acetic acid.

•  Heating processes called pasteurization is used to kill bacteria in some alcoholic beverages and milk.

The Germ theory of disease:

•  Agostino Bassi (1934) and Pasteur (1865) – showed a casual relationship between microorganisms and disease.

•  Joseph Lister (1860s) – introduced the use of disinfectant to clean surgical dressings in order to control infection in humans

•  Robert Koch (1876) – proved that microorganisms transmit disease – Koch's postulates which are used today to prove that a particular microorganism causes a particular disease.

•  Introduced pure cultures

•  Koch's postulates (Henle-Koch's Postulates) are

1. A specific organism should be found constantly in association with the disease.

2. The organism should be isolated and grown in a pure culture in the laboratory.

3. The pure culture when inoculated into a healthy susceptible animal should produce symptoms/lesions of the same disease

4. From the inoculated animal, the microorganism should be isolated in pure culture.

5. An additional criterion introduced is that specific antibodies to the causative organism shouldbe demonstrable in patient's serum.

•  Angelina – American wife of Koch's assistant suggested solidifying broths with agar as an aid to obtaining pure cultures.

•  Koch also developed techniques for isolating organisms. Identified the bacillus that causes tuberculosis and anthrax, developed tuberculin and studied various diseases in Africa and Asia. His studies on Tuberculosis won him Nobel prize for philosophy and medicine in 1905.

Vaccination:

•  Immunity is conferred by inoculation with a vaccine.

•  Edward Jenner(1798 ) – demonstrated that inoculations with cowpox material provides humans with immunity from small pox

•  Pasteur (1880) – discovered that avirulent bacteria could be used as a vaccine for chicken cholera; he coined the word vaccine

•  Modern vaccines are prepared from living avirulent microorganisms or killed pathogens, from isolated components of pathogens, and by recombinant DNA techniques.