History of Microbiology Flashcards
1
Q
What is microbiology
A
- Study of organisms that are too small to be seen with the naked eye (< 0.1 mm = 100 um)
- Most bacteria 0.2 to 2.0 um in diameter, 2 to 8 um in length
- Microbes are excellent models for understanding cellular processes in unicellular and multicellular organisms
- Microbes play important roles in medicine, agriculture, industry and archaeology
2
Q
What are microorganisms
A
- Microscopic organisms, unicellular organisms or cell clusters, some are multicellular
- Oldest form of life, largest mass of living material on Earth, carry out major processes for biogeochemical cycles, live in places unsuitable for others, other life forms require microbes to survive
- Prokaryotic: DNA organised in a single chromosome, no nucleus, mitosis or organelles
- Eukaryotic: DNA organised into multiple chromosomes inside a nucleus, mitotic division and organelles
3
Q
Describe the evolution of microbial life
A
- First cells appeared between 3.8-3.9 billion years ago, atmosphere was anoxic until 2 billion years ago
- Metabolisms were exclusively anaerobic until evolution of oxygen producing phototrophs
- Life was exclusively microbial until 1 billion years ago
- Extent of Microbial Life: Microbes found in almost every environment imaginable, global estimate of 5x1030 cells (oceanic and terrestrial subsurfaces)
- Microbial Biomass: Significant and cells are key reservoirs of essential nutrients
4
Q
Describe the first observations of microbes
A
- 1665: First use of a microscope by Robert Hooke, observed that cork was made up of ‘little boxes’ or ‘cells’, lacked the staining techniques to view microbes clearly but could visualise individual cells through compound microscopes, marked the beginning of the cell theory
- 1676: Antoni van Leeuwenhoek, first reported observations of microorganisms / microbes clearly, made over 500 microscopes, first to view protists, animal sperm and blood cells
5
Q
Describe the evolution of spontaneous generation theory
A
- 1668-1861: The hypothesis that living organisms arise from nonliving matter, according to spontaneous generation a ‘vital force’ forms life
- Redi (1668): Experiments to show that maggots only appeared after flies were allowed to enter a vessel containing decaying meat, in sealed vessels no maggots appeared
- Needham (1745): Heated broths teemed with microbes after it was allowed to cool proposed that microbes developed spontaneously from fluids
- Spallanzi (1765): Suggested airborne microbes were responsible for contaminating Needham’s solutions
- Virchow (1858): Biogenesis, an alternative hypothesis, that living organisms arise from preexisting life
- Louis Pasteur (1861): Demonstrated that microorganisms are present in the air and can contaminate sterile solutions but that air itself does not create microbes
6
Q
What is the first golden age of microbiology and the main discoveries
A
- Period from 1857-1914, rapid advances by Pasteur and Koch lead to development of microbiology, studied chemical activities of microorganisms, improved microscopy and culturing techniques, developed vaccines and surgical techniques
- Pasteur: Demonstrated that life did not arise spontaneously from non-living matter (1822-1895)
- Lister: Performed surgery under aseptic conditions using phenol, proved microbes caused surgical wound infections (1827-1912)
- Koch: Established experimental steps for linking a specific microbe to a specific disease (1843-1910)
- Fermentation, pasteurisation, germ theory, koch’s postulates, vaccinations
7
Q
Describe fermentation and pasteurisation (1st)
A
- Pasteur discovered that yeast ferments sugars to alcohol and that bacteria spoil wine, beer and food
- Pasteurisation is the discovery that sufficient heat could kill spoilage bacteria
- Established relationship between disease and microbes, link between activity of microorganisms and physical / chemical changes in organic materials
8
Q
Describe the germ theory of disease (1st)
A
- The principle that microorganisms cause disease
- 1835-1865: Bassi and Pasteur, silkworm disease caused by fungi and protozoan, developed method for recognising afflicted silkworm moths
- 1840’s: Semmelwise found physicians who didn’t disinfect their hands, routinely transmitted infections from one obstetrical to another, advocated hand washing to prevent transmission of puerperal fever
- 1860’s: Joseph Lister introduced the use of a disinfectant (phenol – carbolic acid) to treat surgical wounds, proved that microorganisms cause surgical wound infections
- 1876: Robert Koch provided proof that a bacterium causes anthrax and provided experimental steps to prove a specific microbe causes a specific disease (Koch’s postulates - 1884)
9
Q
Describe koch’s postulates (1st)
A
- A sequence of experimental steps for directly relating a specific microbe to a specific disease
- Determine aetiology of disease (first step in treatment and prevention)
1. Isolate suspected agent from a disease victim (agent should be found in every disease case)
2. Grow agent in pure culture
3. Infect a healthy and susceptible host (no preexisting immunity) and show that organism produces classical clinical disease
4. Isolate the same organism from the new victim
10
Q
Describe vaccination (1st)
A
- 70 years before Pasteur, Jenner embarked on a way to protect people from small pox, developing the first vaccine (from avirulent microbial strains) to protect from infection (immunity)
11
Q
What is the second / third golden age of microbiology and main discoveries
A
- Second / Third Golden Age: Medical microbiologists set out to search for substances that could destroy pathogenic microbes but didn’t damage infected tissues of the host
- Chemotherapy, synthetic drugs, antibiotics, specialisation, genomics, recombinant DNA
12
Q
Describe chemotherapy and synthetic drugs (2nd)
A
- C: Treatment with chemicals, chemotherapeutic agents used to treat infectious disease can be synthetic drugs or antibiotics
- S: In 1910 Paul Ehrlich described principle of selective toxicity (“magic bullet”) and developed a synthetic arsenic drug, salvarsan, to treat syphilis
13
Q
Describe antibiotics and antibiotic resistance (2nd)
A
- A: Chemicals / antimicrobial agents produced naturally by bacteria and fungi that act against other microorganisms
- Many discovered, often too toxic for human use, few antiviral drugs (reliable on hosts for replication
- In 1928 Alexander Fleming & Howard Florey discovered the first antibiotic, observed that Penicillium fungus made an antibiotic (penicillin that killed S. aureus
- 1930’s: Sulfonamides were synthesised
- 1940’s: Penicillin was tested clinically and mass produced
- AR: Genetic changes in bacteria, encode enzymes to degrade the antibiotic, or cause changes to surface of bacteria to prevent attachment or uptake of the antibiotic
14
Q
Describe specialisations, genomics and recombinant DNA technology (2nd / 3rd)
A
- Specialisation within microbiology: bacteriology, mycology, parasitology, immunology, serology and virology
- Genomics: Study of an organisms genes, provided new tools for classifying and studying microorganisms
- Recombinant DNA: New methods to replicate DNA and RNA, revolutionised research / practical applications, inserts recombinant DNA into bacteria to make large quantities of desired protein
15
Q
What role do microorganisms play and how have they impacted humans
A
- Human Welfare: Food, microbial ecology, bioremediation, biological insecticides, biotechnology, genetic engineering
- Food: Negative (food spoilage by microorganisms requires specialised preservation of many foods) and positive (microbial transformations yield dairy / food products)
- Energy and Environment: Role of microbes in production of methane, ethanol and hydrogen, the role of microbes in cleaning up pollutants (bioremediation)
- Genetic Resources: Exploitation of microbes for production of antibiotics, enzymes, and various chemicals, genetic engineering of microbes to generate products of value to humans
- Human Disease: Humans have a normal flora or microbiota, factors that determine contraction of a disease include disease producing properties of microbe and hosts resistance
