Microbiology was a study of living organisms that scientists had some trouble proving to the general public that they even existed. One of the reasons for this was that people could not see the organism. That is, not until the microscope was invented. Antony van Leeuwenhoek (1674 to 1724) was one of the pioneers in the making of microscopes, His observations are among the first recorded of bacteria, yeasts and protozoa.
Another pioneering microbiologist was Robert Koch (1890) who is known for postulates that help establish the agent for a particular disease. Koch's Postulates:
1. The organism should be associated with the lesions of the disease in all cases and absent from healthy individuals.
2. The organism must be isolated and grown in pure culture outside the diseased host.
3. When this culture is inoculated into a healthy host this host must develop the symptoms of the disease.
4. The organism must be re-isolated from the experimentally infected host grown again in a culture and infect once again a healthy host.

These postulates can be used for human, animals and plants for establishing the disease agent. They are still used today even though some complications and modifications must be used for certain obligate parasitic organisms (must live within a host).

The development and use of the vaccination against smallpox was aided by the work of another early microbiologist Edward Jenner. Edward Jenner was a country doctor working in England around 1798. He observed those individuals who were exposed to cowpox, a related virus that infect cattle, and these individuals did not contract the smallpox virus. He was the first to use an artificial exposure to the cowpox virus to stimulate the human immune response. Edward Jenner's early work put to use one of the first vaccinations for smallpox.

In this discussion share your opinion as to which of these early microbiologists' contribution was the most important and describe your reasoning. Remember to comment on a classmate's response as well. Please contribute before the second Friday of the module.