1. A Brief History of Microbiology
Lecture #03
A Brief History of Microbiology
Amjad Khan Afridi
Lecturer,
Health & Biological Sciences
Abasyn University Peshawar

2. Microbiology The study of microorganisms.
Microorganisms: Small living organisms that generally can not be seen with the naked eye.
Include:
Bacteria
Fungi (yeasts and molds)
Protozoa
Algae
Multicellular parasites
Also include nonliving infectious agents:
Viruses
Prions

3. Earth: Have many important and beneficial biological functions:
Microbes are Essential for Life on
Earth: Have many important and beneficial biological functions:
Photosynthesis: Algae and some bacteria capture energy from sunlight and convert it to food, forming the basis of the food chain.
Decomposers: Many microbes break down dead and decaying matter and recycle nutrients that can be used by other organisms.
Nitrogen Fixation: Some bacteria can take nitrogen from air and incorporate it into soil.

4. Important and beneficial biological functions of Microbes
Digestion: Animals have microorganisms in their digestive tract, that are essential for digestion, vitamin synthesis, and overall health.
Cellulose digestion (termites, cows, rabbits, etc.)
Vitamin K and B synthesis in humans
Prevent the overgrowth of pathogenic bacteria and yeast
Medicine: Many antibiotics and other drugs are naturally synthesized by microbes.
Penicillin is made by a mold

5. Penicillin is Produced by a Mold

6. Important and beneficial biological functions of Microbes
Food Industry: Many important foods and beverages are made with microbes:
Alcoholic beverages (Wine, beer, rum, whiskey)
Bread
Vinegar
Soy sauce
Cheese
Pickles, olives, sauerkraut
Yogurt
Buttermilk
Sour cream
Coffee
Chocolate
Hams, sausages

7. Important and beneficial biological functions of Microbes
Genetic Engineering: Recent advances in gene splicing allow us to design recombinant microbes that produce important products:
Human growth hormone (Dwarfism)
Insulin (Diabetes)
Blood clotting factor (Hemophilia)
Recombinant vaccines
Hepatitis A and B vaccines
Human hemoglobin (Emergency blood substitute)
Taxol (Breast and ovarian cancer)
Erythropoietin (Anemia)
Monoclonal antibodies (Disease diagnosis and prevention).

8. Important and beneficial biological functions of Microbes
Medical Research: Microbes are well suited for biological and medical research for several reasons:
Relatively simple and small structures, easy to study.
Genetic material is easily manipulated.
Can grow a large number of cells very quickly and at low cost.
Short generation times make them very useful to study genetic changes.

9. Microbes and Disease
Most microbes are either beneficial or harmless to humans.
Less than 1% of microbes cause disease.
In 1962, the surgeon general of the United States stated: “The war against infectious diseases has been won”.
Today it is clear that this was overly optimistic:
Emerging diseases: New diseases like AIDS, hantavirus, Ebola fever, Lyme disease, Hepatitis C, and others that did not exist a few years ago.
Antibiotic and Drug Resistance: Many old diseases are becoming resistant to traditional therapies: Tuberculosis, gonorrhea, malaria, etc.
Today infectious diseases cause 50% of the 52 million worldwide deaths per year.

10. Infectious Diseases Causing Most Deaths Worldwide in 2000
Disease Cause Deaths/year
Acute Respiratory*Bacterial or viral 4,400,000
Diarrheal diseases Bacterial or viral 3,200,000
Tuberculosis Bacterial 3,100,000
Malaria Protozoan 3,100,000
Hepatitis B Viral 2,000,000
Measles Viral 1,500,000
AIDS Viral 1,000,000
Neonatal Tetanus Bacterial 600,000
*: Pneumonia, bronchitis, influenza, etc.

11. History of Microbiology
Physics began in ancient times, mathematics even earlier, but the knowledge of tiny living things, their biology, and their impact on human lives have only been around since the late 19th century.
Until about the 1880s, people still believed that life could form out of thin air and that sickness was caused by sins or bad odors.
عذاب الہی، زہریلے بخارات، لعنتیں، جادوگری،
Germ theory of Disease 1857: Germ Theory of Disease: Belief that microbes cause diseases. Before, most people believed diseases were caused by divine punishment, poisonous vapors, curses, witchcraft, etc.

12. Discovery of Microbes and the Dawn of Microbiology
Microbiology is the study of living organisms of microscopic size.
The term microbiology was given by French chemist Louis Pasteur ( ).
Microbiology is said to have its roots in the great expansion and development of the biological sciences that took place after 1850.
The term microbe was first used by Sedillot (1878).

13. History of Microbiology
Early Studies
Before 17th century, study of microbiology was hampered by the lack of appropriate tools to observe microbes.
Robert Hooke: English scientist
In 1665 built a compound light microscope and used it to observe thin parts of cork. Coined the word cell.

14. History of Microbiology
Early Studies
Anton van Leeuwenhoek ( )
Was Dutch amateur biologist 
In 1673 was the first person to observe live microorganisms (bacteria and protozoa) which he called “animalcules” (little animals), using single-lens microscopes that he designed (homemade microscopes).
He is known as the “Father of microbiology”.
Leeuwenhoek is also considered to be the father of bacteriology and protozoology (protistology).
He wrote over 200 letters which were transmitted as a series of letters from to Royal Society in London during a 50 years period.

15. History of Microbiology
Spontaneous Generation vs Biogenesis
Before 1860s many scientists believed in Spontaneous generation, i.e.: That living organisms could arise spontaneously from nonliving matter:
Mice come from rags in a basket.
Maggots come from rotting meat.
Ants come from honey.
Microbes come from spoiled broth.

16. History of Microbiology Spontaneous Generation vs Biogenesis
Theory of Biogenesis: Belief that living cells can only arise from other living cells.
Francesco Redi: In 1668 proved that maggots do not arise spontaneously from decaying meat.
Lazaro Spallanzani: In 1765 found that nutrient broth that had been heated in a sealed flask would not become contaminated with microbes.
Some proponents of spontaneous generation argued that boiling had destroyed the “life force” of air in flask.
Others argued that microbes were different from other life forms.
12th, October, 2022

17. History of Microbiology Spontaneous Generation vs Biogenesis
Debate was finally settled by Pasteur.
Louis Pasteur: In 1861 finally disproved spontaneous generation when he demonstrated that microorganisms in the environment were responsible for microbial growth in nutrient broth.
Designed swan neck flasks that allowed air in, but trapped microbes in neck.
Developed aseptic technique: Practices that prevent contamination by unwanted microorganisms.

18. Pasteur’s Swan Neck Experiment

21. History: Pasteur’s Conclusions
The bended neck allowed air to enter the bottle and the liquid but trapped any particulates including microorganisms.
No microbial growth as long as the liquid broth did not come in contact with the microbes.
Hence air alone was not sufficient to generate life.
Pasteurization, Disease Causes, Vaccine, Fermentation

22. History of Microbiology
Golden Age:
Rapid advances led to the development of microbiology as a science.
Pasteur’s Contributions to Microbiology:
Fermentation: Pasteur found that yeasts were responsible for converting sugar into alcohol in the absence of air.
Souring and spoilage were caused by bacterial contamination of beverages.

23. History of Microbiology
Golden Age:
Pasteur’s Contributions:
Pasteurization: Developed a process in which liquids are heated (at 65oC) to kill most bacteria responsible for spoilage.
Disease Causes: Identified three different microbes that caused silkworm diseases.
Vaccine: Developed a vaccine for rabies from dried spinal cords of infected rabbits.
Directed Pasteur Institute until his death in 1895.
Thermization: Heat the milk to between 57°C to 68°C and hold for 15 minutes.
Batch pasteurization: Also known as low-temperature long time (LTLT) pasteurization
Flash pasteurization: Also known as high-temperature short time (HTST) pasteurization
Robert Koch (1876): first time introduced diseases pathogens

24. Pasteur Institute, 1887
The Pasteur Institute is a French non-profit private foundation dedicated to the study of biology, micro-organisms, diseases, and vaccines. It is named after Louis Pasteur, who invented pasteurization and vaccines for anthrax and rabies. The institute was founded on 4 June 1887, and inaugurated on 14 November 1888

25. History of Microbiology
Golden Age:
Germ Theory of Disease: Belief that microbes cause diseases. Before, most people believed diseases were caused by divine punishment, poisonous vapors, curses, witchcraft, etc.
Agostino Bassi (1835): Found that a fungus was responsible for a silkworm disease.
Ignaz Semmelweis (1840s): Demonstrated that childbirth fever was transmitted from one patient to another, by physicians who didn’t disinfect their hands. He was ostracized by colleagues.
عذاب الہی، زہریلے بخارات، لعنتیں، جادوگری،
Robert Koch (1876): Puerperal feve

26. History of Microbiology
Golden Age:
Germ Theory of Disease:
Joseph Lister (1860): Used disinfectant to treat surgical wounds, greatly reducing infection rates. Considered the father of antiseptic surgery.
Robert Koch (1876): First person to conclusively prove that a specific bacterium caused a disease.
Germ Theory: One microbe causes one specific disease.
Proved that Bacillus anthracis causes anthrax in cattle.
Later identified bacterium that causes tuberculosis.

27. History of Microbiology Modern Microbiology: After 1914
Chemotherapy: Treatment of a disease by using a chemical substance. Chemical must be more poisonous to microbes than host.
Quinine: First known chemical to treat a disease (malaria). Used by Spanish conquistadors.
Synthetic Drugs: Made in the laboratory.
Antibiotics: Produced naturally by fungi and bacteria.

28. History of Microbiology Modern Microbiology: After 1914
Alexander Fleming (1928): Discovered that penicillin produced by the mold Penicillium notatum was able to prevent microbial growth.
Penicillin was not mass produced until the 1940s.
Rene Dubos (1939): Discovered two antibiotics (gramidin and tyrocidine) produced by bacterium (Bacillus brevis).
Paul Ehrlich (1910): Search for “magic bullet”.
Discovered salvarsan, an arsenic derivative, was effective against syphilis.
The discovery of penicillin and the initial recognition of its therapeutic potential occurred in the United Kingdom, but, due to World War II, the United States played the major role in developing large-scale production of the drug, thus making a life-saving substance in limited supply into a widely available medicine

29. History of Microbiology Modern Microbiology: After 1914
Problems with Chemotherapy:
Toxicity
Drug resistant microbes

30. Diversity of Microorganisms I. Bacteria (Sing. Bacterium)
Small, single-celled (unicellular) organisms.
Procaryotes: “Before nucleus”.
Lack the following structures:
Nuclear membrane around DNA
Membrane bound organelles
Mitochondria
Chloroplasts
Golgi apparatus
Endoplasmic reticulum
Lysosomes

31. Kingdom Prokaryotae: Bacteria lack nucleus and membrane bound organelles

32. Diversity of Microorganisms I. Bacteria (Sing. Bacterium)
Include two groups:
Eubacteria: Peptidoglycan cell walls.
Archaebacteria: Lack peptidoglycan cell walls.
Shapes: Several forms:
Bacilli: Rod like. (Sing. Bacillus)
Cocci: Spherical. (Sing. Coccus)
Spiral: Corkscrew or curved
Square
Star shaped
The characteristics of Eubacteria are:
They are unicellular, prokaryotic microscopic cells.
The cell wall is made up of Peptidoglycan (Murein).
They can be divided into two parts - Gram-positive bacteria and Gram-negative bacteria.
It moves with the help of flagella.
Rhizobium and Clostridium are two eubacteria

34. Diversity of Microorganisms I. Bacteria (Sing. Bacterium)
Divide by binary fission (not mitosis).
Source of nutrients varies:
Heterotrophs: Consume organic chemicals.
Autotrophs: Make their own food. Include photosynthetic bacteria.
Motility: Many can “swim” by using moving appendages:
Cilia: Small hair like structures
Flagella: Large whip like structures.
Distinguish between motility and Brownian motion.

35. Diversity of Microorganisms II. Fungi (Sing. Fungus)
Eucaryotes: “True nucleus”
DNA is surrounded by nuclear membrane.
Cells have membrane bound organelles: Mitochondria, endoplasmic reticulum, etc.
Cells are larger than those of procaryotes.
May be unicellular or multicellular:
Unicellular: Yeasts
Multicellular: Molds, mushrooms
Do not carry out photosynthesis.
Must absorb organic nutrients from their environment.

36. Diversity of Microorganisms II. Fungi (Sing. Fungus)
Source of nutrients varies:
Saprotrophs: Decomposers that feed on dead and decaying matter. Most fungi are decomposers.
Parasites: Obtain nourishment by parasitizing live animals and plants.
Cell wall made of chitin.
May reproduce sexually or asexually.

37. Diversity of Microorganisms III. Protozoa (Sing. Protozoan)
Eucaryotes: “True nucleus”
DNA is surrounded by nuclear membrane.
Cells have membrane bound organelles and are larger than those of procaryotes.
Unicellular
Kingdom Protista
Sexual or asexual reproduction
Classified based on locomotion:
Pseudopods: “False feet”. Cytoplasmic extensions.
Example: Amoeba

38. Protozoa Belong to Kingdom Protista: Eucaryotic Unicellular or Simple Multicellular Organisms

39. Diversity of Microorganisms III. Protozoa (Sing. Protozoan)
Classified based on locomotion:
Flagella: Long whip like appendages.
Example: Trichomonas vaginalis, causes trichominiasis, a sexually transmitted disease.
Cilia: Small hair like appendages
Non-motile: Do not move in their mature forms.
Example: Plasmodium spp., causative agent of malaria.

40. Diversity of Microorganisms IV. Algae (Sing. Alga)
Eucaryotes: “True nucleus”
Photosynthetic: Important part of food chain because produce oxygen and carbohydrates used by animals.
Unicellular or multicellular
Kingdom Protista
Sexual or asexual reproduction
Cell walls composed of cellulose
Found in aquatic environments (oceans, lakes, rivers), soil, and in association with plants.

41. Diversity of Microorganisms V. Viruses
Acellular infectious agents, not considered living because they lack cells.
Obligate intracellular parasites: Viruses can only reproduce by using the cellular machinery of other organisms.
Simple structure:
Protein coat (capsid) with either DNA or RNA, but not both.
May also have a lipid envelope.

42. Comparison of Cells and Viruses

43. Diversity of Microorganisms VI. Multicellular Animal Parasites
Eucaryotes: “True nucleus”
Multicellular animals, usually are visible to the naked eye.
Microscopic during some stages of life cycle.
Spend part or all of their lives inside an animal host.
Helminths include:
Flatworms (Platyhelminths): E.g. Tapeworm
Roundworms (Nematodes): E.g. Ascaris, pinworm.

44. 18th October, 2022