Microbiology- History

Scientists 1500-1700

Hans Janssen and Zacharias Janssen (1590s)

• the Dutch spectacle‑making duo widely credited with creating the first compound (binocular‑style) microscope in the 1590s.

Hooke (1665)

• cellular composition of cork and introduction of the word “cell” to science

Francesco Redi (1668)

• test spontaneous generation with experiment. Meat with lid vs meat w/o lid = maggots. Then added mesh meat variable.

Antoni Van Leeuwenhoek (1683)

• resolution improves as lens polishes

• “anamacules” discovered

• discovered bacteria from saliva

• dutch linen merchant

• first to observe living microbes

• single lens magnified up to 300x

• sperm: thought a human was fully in sperm from dad

Scientists 1700- 1850

Louis Jablot (1710)

• boiled hay infusions; reasoned that even microscopic organisms must have parents *thought dust might be culprit*

• heat up 2 things to kill bacteria. leave one open, one with lid. one open gets bacteria

John Needham

• boiled mutton gravy. different outcome than jablot.

• determined organic matter had a vital force

• endospores dont die from just boiling

• higher pressure

Lazzaro Spallanzani (1765)

• tested needham

• found that a “hermetic” deal was required to prevent microbial growth

Matthias Schleiden

• all plants made of cells

Theodor Schwann (1839)

• all animals made of cells

Cell Theory

Rudolph Virchow (1855)

• “Cellular Pathology”

• living things come from other living things

• came from robert renak

• origin of cells by division of preexisting cells

Cell theory

1. all living things made up of cells

2. cells basic unit of structure and function in living things

3. living cells come only from other living cells

Light

resolution

• wavelength/ 2 (numerical aperture)

• refraction occurs when light bounces

• straight pole bends at angle as enters water. large difference between refractive indices of air & water

• lens collection of prisms; light passes convex lens it is refracted toward focal point on the other side of the lens. focal length is distance to focal point

Visible spectrum of light

(infrared) ROY G BIV (ultraviolet)

700nm —————> 400nm wavelength

insert spectrum

Brightfield image vs. Phase contrast image

unstained brightfield invisible

TEM machine- show 3D

TED Talk- Martin Hanczyc: the line between life and nonlife

living systems

• body

• metabolism (convert resources into building block)

• inheritable information

  • movement replication

  • evolution: synthesis of

viruses arent alive: no cells

Living characteristics

• growth

• metabolism (breathing & breaking food down)

• Hereditary information (DNA)
  heredity (reproduction)

• movement

• cellular

Scientists (1860s-1900s)

Louis Pasteur (1862)

• studying beer and wine. “father of microbiology”

• schwann neck flask gives air into flask. Boil. one broken stem one not. broken stem has microbial growth

John Tyndall

• microbes in air and dust have high heat resistance.

• boiling doesnt kill endospores. can have them turn back to vegetative cell

• tyndalization: fractional sterilization designed to destroy spores indirectly. prep is exposed to flowing stem for hour, then material allowed to incubate to permit spore germination. resultant vegetative cells destroyed by repeated steaming incubation. “STERILE:- void of life

Ferdinand Cohn

• cohn determined forms to be heat resistant endospores

• Any life including endospores- nonsterile

Vaccinations and Variolation

Edward Jenner

• small pox similar to cow pox. People with cowpox doesn’t get small pox.

• gave kid cow pox. Later gave him small pox and he didn’t get it.

• “father of immunology”

Lady Mary Wortley Montagu

• intro inoculation against smallpox to europe

• protection against disease by giving child pus

• variolation: deliberately exposing a healthy person to material from a smallpox sore (usually dried scabs or pus). The goal was to cause a mild, controlled infection that would give the person lifelong immunity.

In australia cervical cancer could soon be eliminated

• 3 dose course for hpv for teenage girls

• given to kids

Cleaning

Oliver Wendel Holmes

• mothers give birth at home fewer infections than hospital birth

Dr. Ignaz Semmelweis

• women became infected in maternity ward after examinations by physicians coming from autopsy room

Joseph Lister

• aseptic techniques to reduce microbes in medical setting and preventing wound infetion

• washing hands, spraying air with strong anti septic chemicals like phenol prior to surgery

Florence Nightingale

• setting standards of hygiene

Robert Koch

• anthrax in cattle. Bacillus anthracis

• Koch’s postulates- sequence of experimental steps that verified the germ theory

  • identified cause of anthrax, TB, and cholera

  • developed pure culture methods (1 species being grown)

1. microorganisms isolated from dead animal

2. microorganisms grown in pure culture

3. microorganisms identified

4. microorganisms injected into healthy animals

5. disease reproduced in second animal

6. microorganisms are grown in pure culture

7. identification of identical microorganisms

exceptions

• microorganisms are unable to be cultured on artificial media

• 2 or more organism work in synergy to cause disease

• symptoms and diseases can be caused by any one of several microbes

To prove that a specific microorganism causes a specific disease.

They provide a systematic, scientific method for linking a pathogen to the illness it produces. Before Koch, people suspected microbes caused disease, but there was no experimental proof. His postulates created the first evidence‑based framework for identifying infectious agents.

Microbiology terms

• Microbiology — The study of microorganisms and their interactions with humans, animals, plants, and the environment.

• Plankton — Tiny drifting organisms in aquatic environments that serve as the base of many food webs.

• Pathogen — A microorganism capable of causing disease in a host.

• Bacteria — Single‑celled prokaryotic microorganisms that reproduce quickly and inhabit nearly every environment.

• Protozoa — Single‑celled eukaryotic organisms that often live in water and may cause disease.

• Fungi — Eukaryotic organisms such as yeasts, molds, and mushrooms that absorb nutrients from their environment.

• Helminth — A parasitic worm that infects hosts and causes disease.

• Prokaryotic — Describes cells lacking a nucleus and membrane‑bound organelles.

• Eukaryotic — Describes cells that contain a true nucleus and membrane‑bound organelles..

• Eukaryote — An organism whose cells contain a true nucleus and membrane‑bound organelles.

• Prokaryote — An organism whose cells lack a nucleus and membrane‑bound organelles.

How broad is the scope of microbiology? (Hint: see all the fields of study”ologies” above) Identify fields of microbiology that affect "everyday living")

Microbiology Subfields (Small Definitions)

• Bacteriology — Study of bacteria and their roles in health, disease, and the environment. Affects food safety, probiotics, antibiotics, gut health, and environmental cleanup.

• Mycology — Study of fungi, including yeasts, molds, and mushrooms. Impacts food production (bread, cheese), medicine (penicillin), and fungal infections.

• Protozoology — Study of protozoa, single‑celled eukaryotic microorganisms. Relevant to waterborne diseases, sanitation, and environmental health.

• Virology — Study of viruses and how they infect hosts. Relates to common illnesses (colds, flu), vaccines, antiviral drugs, and public health

• Parasitology — Study of parasites and the diseases they cause. Connects to water safety, foodborne parasites, and prevention of vector‑borne diseases.

Microbial Structure & Function

• Morphology — Study of the shape, size, and structure of microorganisms.

• Microbial Physiology — Study of how microbes function, grow, and metabolize. Affects fermentation (yogurt, beer), waste treatment, and industrial enzyme production.

Classification & Genetics

• Taxonomy — Science of naming, classifying, and organizing organisms. Helps identify microbes in food, water, medicine, and clinical labs.

• Molecular Biology — Study of biological processes at the DNA, RNA, and protein level. Used in genetic testing, forensic science, biotechnology, and medical diagnostics.

Host–Microbe Interaction & Disease Spread

• Immunology — Study of the immune system and how it defends against microbes. Shapes vaccines, allergies, autoimmune disorders, and how your body fights infections.

• Epidemiology — Study of how diseases spread, who they affect, and how to control outbreaks. Influences disease tracking, outbreak control, public health guidelines, and risk reduction.

Know the appropriate scientific terminology applied to the three shapes of bacteria (coccus, bacillus, and spirillum, and be able to describe each.

1. Coccus (plural: cocci)

Shape: Spherical or round
Description:

• Look like little dots or beads

• Can appear alone or in characteristic arrangements

  • Diplococci — pairs

  • Streptococci — chains

  • Staphylococci — clusters (grape‑like)

2. Bacillus (plural: bacilli)

Shape: Rod‑shaped
Description:

• Cylindrical, longer than they are wide

• Arrangements include:

  • Diplobacilli — pairs

  • Streptobacilli — chains

  • Coccobacilli — very short rods that look almost round

3. Spirillum (plural: spirilla)

Shape: Rigid spiral or corkscrew
Description:

• Spiral‑shaped with a stiff, helical form

• Move using external flagella

• Not to be confused with spirochetes, which are flexible spirals with internal flagella

What are bacterial endospores

Bacterial endospores are highly resistant, dormant structures formed by certain bacteria (like Bacillus and Clostridium) to survive extreme conditions such as heat, drying, chemicals, and radiation.

• Purpose: Survival, not reproduction.

• Why they matter: Endospores can withstand boiling, disinfectants, and harsh environments.

• When they form: When nutrients are low or conditions become unfavorable.

• Why they’re dangerous: Some cause serious diseases (e.g., tetanus, anthrax, botulism).

• How to destroy: Requires autoclaving or Tyndallization—normal boiling is not enough

How did Louis Pasteur disprove the theory of Spontaneous Generation? What problems remained (see your notes about John Tyndall and or text discussion of Needham)

How did Pasteur disprove Spontaneous Generation?

• With swan‑neck flasks that allowed air in but trapped dust. Broth stayed sterile unless it touched dust, proving microbes come from other microbes—not from nonliving matter.

What problem remained after Pasteur’s experiment?

• Some broths still produced growth after boiling, leading critics to claim spontaneous generation still occurred.

How did John Tyndall resolve this problem?

• He discovered heat‑resistant spores and showed dust carried them. He created Tyndallization to kill spores, explaining why Needham’s experiments were flawed.

Describe process of Tyndallization

1. Heat the Material (Day 1) Critical Step

• The first heating cycle kills all vegetative (actively growing) microbes.

• Vegetative cells die, but spores survive

• Allow material to cool and sit overnight

2. Incubate to Allow Spore Germination Biology Principle

• Cooling and resting the material encourages surviving spores to germinate.

• Spores transform into vegetative cells, which are easier to kill

3. Repeat Heating (Day 2)

• The second heating cycle kills the newly germinated vegetative cells.

• Spores that did not germinate may still remain

4. Repeat Incubation

• Another rest period allows any remaining spores to germinate.

• Ensures maximum spore germination before final heating

5. Final Heating (Day 3)Sterilization Achieved

• The last heating cycle destroys all remaining vegetative cells.

• All vegetative cells are now eliminated

• Material is considered sterile