History of Microbiology

1. History of Microbiology

2. Spontaneous Generation • Spontaneous Generation is the Theory that life come from inanimate objects or non-living things. • The Theory of Spontaneous Generation was disproved and Microbiology was founded by some amazing scientists. Let’s briefly review some of these scientists.

3. In 1668-Redi devised an experiment to disprove the Theory of Spontaneous Generation • He put some meat inside jars and covered them. No maggots grew. • Antagonists claimed life needed fresh air to grow so the experiment was invalid. • Redi repeated the experiment but used gauze to cover the jars allowing fresh air in, but keeping flies out. No maggots grew.

4. Antony Leeuwenhoek: owned dry-good store (Holland 1632) • Heard about grinding lenses out of glass to make things look larger • Visited spectacle makers to learn how to grind lenses • Visited alchemists and apothecaries to learn how to get metal from ore • Visited gold- and silversmiths to learn their trade • Put it together to make a microscope

5. Animalcules • Leeuwenhoek discovered living cells while looking under his microscope. • He called the living cells, “Animalcules”. • Animalcules were defined as tiny animals simple enough to be derived from non-living material.

6. “Vegetative-Force” • Spallanzani vs. Needham: • Spallanzani: Italy 1729, became a priest to the Catholic Church • Inspired by Redi’s research • Needham: Western Europe, priest to catholic church (same years as Spallanzani) • Boiled mutton gravy and corked flasks, returned to discover that their were microbes swimming in the gravy • Concluded that the juice created the microbes

7. Spallanzani: He did not believe Needham’s conclusions and devised his own experiment to disprove the theory. Spallanzani put various seeds and pure water into flasks, sealed them and boiled them for hours Sealed flasks, No microbes Corked flasks, microbes Needham: In return, Needham published a paper about the vegetative force, “the force that is the source of creation”. He claimed that Spallanzani’s experiments were invalid because boiling the juice for so long weakens the vegetative force

8. The Theory of Biogenesis • 1858-Pasteur proved that living cells arise only from preexisting living cells. • In other words, life only comes from life. • His experiment consisted of flasks with S-curve in the neck of the bottle • The S-curve would allow air into the bottle but would trap any contaminants, such as mold spores, in the air in the neck of the flask. • He boiled some broth and it remained sterile. • Pasteur’s experiment became the basis of aseptic techniques • For example, pasteurization of milk and other food products. Bacteria cause spoilage of food products but by raising the temperature high enough to kill the organisms, the food remains unspoiled for a longer period of time. • Pasteurization is still used today

9. Germ Theory of Disease • Germ Theory of Disease is the idea that microorganisms may cause disease. • This theory was hard for many people to accept because disease was believed to be punishment for crimes or misdeeds • In the 1860’s Lister, a physician, applied Germ Theory to medical procedures • He noticed that many patients would die following surgery, not from the original problem but from infection following the surgery. • He treated surgical wounds with phenol (carbolic acid) and other surgeons eventually adopted. • Many lives were saved once this procedure was adopted.

10. Proof that Bacteria Cause Disease • Koch worked with Bacillus anthracis, the organism that causes anthrax. • 1. He found the organism in blood of dead animals. • 2. Cultured organisms • 3. Injected culture into healthy animals • 4. Animals developed disease and died • 5. Found same organism in blood • Koch developed the steps for identifying the causative agent (organism that causes the disease) of disease. These steps are called Koch’s Postulates. • Koch’s postulates led to development of Scientific Method which is still used today in conducting research.

11. Smallpox (1st vaccination) • Milkmaid worked around cows with cowpox. • She informed Edward Jenner (British Physician) that couldn’t get smallpox because she had been exposed to cowpox. • Jenner put her theory to the test by using scrapings from cowpox blisters. • A mother volunteered her son to be experimented on because she desperately wanted him to be safe from smallpox.

12. Jenner scraped his arm and put in scrapings from the cowpox blister into the wound. The boy developed a small sore that quickly cleared up. Then Jenner injected him with smallpox to see if he would get sick. He was immune to the disease. • This procedure was called vaccination. The word vaccination was derived from the latin word vacca, meaning cow.

13. Some Understanding of Immunity • 1880-Pasteur noticed that the organism that causes fowl cholera lost ability to cause disease after grown in lab for long periods. • Pasteur was experimenting with fowls and fowl cholera. He started with a very virulent (see definition below) strain of the disease. Each time he would inject a new bird with the organism it would die. • Over time he noticed that the birds began to live in spite of the injections with the disease. • Then he noticed that when he injected them again with a fresh new strain, they still didn’t get sick.

14. Pasteur conluded that the strain that had been grown in the lab for a long period of time was still able to cause an immune response, but it wasn’t strong enough to make the bird sick. Thus the animals became immune to the disease. • Definitions: • Virulent: able to cause disease • Avirulent: unable to cause disease

15. Drug Treatment • Sulfa drugs were the first type of medicine prescirbed for infections. • Made from dyes used for fabrics • Antibiotics were discovered first in 1928. • Alexander Fleming was conducting experiments with bacteria on agar plates. In the process of one experiment he discovered that his plates had been contaminated with mold (Penicillium notatum). He threw those plates in the trash. • Then he started to think about what he had seen on those plates and retrieved them from the trash can. He noticed that all around the mold was an area where bacteria was not growing. It occurred to him that the mold must be killing the bacteria. That was how penicillin was discovered. • Many antibiotics that we use today are made by other organisms.

16. A problem that physicians and scientists face today is microorganisms becoming resistant to antibiotics • Vancomycin resistant Staphylococcus areus and Enterococcus faecalis, may become untreatable if they continue to acquire drug resistance. Then the infection will not be able to be stopped. • Unfortunately it is very time consuming to conduct the research necessary to discover new antibiotics and costly to manufacture synthetic drugs. So it may be years before a new family of antibiotics is available to use.

17. Microbes and Human Disease • Definiton: Normal microbiota or flora • Normal variety of microbes that live on or inside our bodies • Occassionally normal microbiota can make us sick or infect people with whom we come in contact (opportunistic pathogen) • An opportunistic pathogen is one that can cause disease when the conditions are right, the immune system is suppressed or the body is weakened in some way. • Emerging Infectious Diseases • BSE, AIDS, Hanta, Ebola, Dengue, Cryptosporidum

18. Modern Microbiology • Microbiology is now divided into several separate fields of study. • Bacteriology: study of bacteria. • 1997-new bacterium discovered, Thiomargarita namibiensis • All organisms going through reclassification due to genomic studies • Previously classified according to visual characteristics and metabolic characteristics • Mycology: study of fungi. • Increase in fungal infections by Coccidioides immitis • Parisitology: study of parasites. • protozoa and parasitic worms continually found.

19. Immunology: study of the immune system • Dates back to Edward Jenner (1796) • Some vaccines developed since, but new vaccine research is rapidly growing due to ability to manipulate DNA • Eradication of Smallpox • Biggest challenge is AIDS, still no known cure and no vaccine possibilities yet. • Destroys immune system

20. Virology: study of viruses • Tobacco Mosaic Disease: disease that kills tobacco plants that is caused by a virus • When scientists first tried to study it, they tried looking for it under the microscope but couldn’t see anything. • Then they tried isolating it by grinding up the leaves and passing the mixture through a bacterial filter. • It was believed that infectious organisms would not pass through an unglazed filter made of porcelain because the pore size is so small. • The infecting organism passed right through the filter and they could not isolate it at that time. • The juice that passed through the filter still containing the virus was called a “Contagious living fluid”, which is what the latin word virus means.

21. Leading up to Genetic Engineering • 1944-Discovery of DNA as genetic material of the cell • 1946-Discovery of conjugation, a method of transfering DNA between living bacterial cells. • 1953-Watson and Crick proposed model for structure and replication of DNA

22. Conclusion • There are many men and women who have contributed to our understanding of Microbiology over the years. I am constantly amazed by the brilliance of their experiments and the fascinating discoveries they made. • I hope that through this course you will discover and understand the amazing world of Microbiology is too.