MICROBIOLOGY AND IMMUNITY

•The first microbes were observed in 1673.
•In 1665, Robert Hooke (Englishman) reported that living things were composed of little boxes or cells.
•1673-1723, Antoni van Leeuwenhoek (Dutch) described live microorganisms that he observed in teeth scrapings, rain water, and peppercorn infusions.
•Many believed spontaneous generation: life can arise from non-living matter
•In 1668, the Italian physician Francesco Redi performed an experiment to disprove spontaneous generation.
•Can you think of an experiment that could disprove spontaneous generation?
•Redi filled six jars with decaying meat

Conditions                                                                Results
•3 open jars                                                              Maggots appeared
•3 jars covered with                                               No maggots fine net
•
•From where did the maggots come?
•What was the purpose of the sealed jars?
•Spontaneous generation or biogenesis?
•Rudolf Virchow (German) presented biogenesis: living cells can arise only from preexisting cells.
•So now there are two hypotheses:
•The hypothesis that living organisms arise from nonliving matter is called spontaneous generation. According to spontaneous generation, a “vital force’ Forms life.
•The Alternative hypothesis, that the living organisms arise from preexisting life, is called biogenesis.
•1861: Louis Pasteur demonstrated that microorganisms are present in the air.

Conditions	Results
Nutrient broth placed in flask, heated, not sealed	Microbial growth
Nutrient broth placed in flask, heated, then sealed	No microbial growth

•The Golden Age of Microbiology 1857-1914
•Beginning with Pasteur’s work, discoveries included the relationship between microbes and disease, immunity, and antimicrobial drugs
•Pasteur showed that microbes are responsible for fermentation.
•Fermentation is the conversation of sugar to alcohol to make beer and wine.
•Microbial growth is also responsible for spoilage of food.
•Bacteria that use alcohol and produce acetic acid spoil wine by turning it to vinegar (acetic acid).
•Pasteur demonstrated that these spoilage bacteria could be killed by heat that was not hot enough to evaporate the alcohol in wine. This application of a high heat for a short time is called pasteurization.
The Germ Theory of Disease
•1835: Agostino Bassi showed a silkworm disease was caused by a fungus.
•1865: Pasteur believed that another silkworm disease was caused by a protozoan.
•1840s: Ignaz Semmelwise advocated handwashing to prevent transmission of puerperal fever from one OB patient to another.
•1860s: Joseph Lister used a chemical disinfectant to prevent surgical wound infections after looking at Pasteur’s work showing microbes are in the air, can spoil food, and cause animal diseases.
•1876: Robert Koch provided proof that a bacterium causes anthrax and provided the experimental steps, Koch’s postulates, used to prove that a specific microbe causes a specific disease.
•Koch was a physician and Pasteur’s young rival
•A young milkmaid informed the physician Edward Jenner that she could not get smallpox because she had already been sick from cowpox.
•1796: Edward Jenner inoculated a person with cowpox virus. The person was then protected from smallpox.
•Called vaccination from vacca for cow
•The protection is called immunity
•1928: Alexander Fleming discovered the first antibiotic.
•He observed that Penicillium fungus made an antibiotic, penicillin, that killed S. aureus.
•1940s: Penicillin was tested clinically and mass produced.
•Angelina Hesse: Development of Agar Used to Grow Microorganisms.

•Although the microscope was invented in the 1600’s, it took 200 years for scientists to discover its use in isolating and identifying specific microbes for a particular disease.