The Main Themes in Microbiology
The Scope of Microbiology
Reference: https://sites.google.com/site/rccmicrobiology/chapter-1-the-main-themes-in-microbiology
- Microbiology: specialized area of biology that deals with living things that are too small to see with the naked eye.
- Microorganism (microbe): organism that is too small too small to see with the naked eye.
- 95-99% microbes are harmless to man.
- Major groups of microorganisms.
- Bacteria
- Algae
- Protozoa
- Fungi
- Helminths (Parasitic Worms)
- Viruses
- Macroscopic organisms: organisms visible to the naked eye.
- Microbes are more accessable due to simplicity, rapid reproduction, and adaptibility.
- Applications of microbiology:
- Immunology: study of the system of defences that protects againsts infections.
- Includes serology, study of blood serum which involves looking for antibodies in the blood to diagnose infectious disease.
- Also includes allergies, a conditoin of hypersensitive response from the immune system to harmless materials.
- Public Health Microbiology and Epidemiology
- Monitor and control the spread of diseases in communities.
- Food Microbiology, Dairy Microbiology, Aquatic Microbiology
- Examine the ecological and practical roles of microbes.
- Agricultural
- Improving yields and combating disease.
- Biotechnology
- Any process in which human use the metabolism of living things for a desired product.
- Industrial
- Use microbes to produce large quantities of substance.
- Genetic Engineering and Recombinant DNA Technology
- Techniques that deliberately alter the genetic makeup of organisms to mass-produce human hormones and drugs.
- Microbial Involvement in Energy and Nutrient Flow
- Photosynthesis
- Formation of food using energy derived from the sun.
- Photosynthetic organisms account for 50% of earth's photosynthesis (alga & cyanobacteria).
- Contribute oxygen to atmosphere.
- Decomposition
- Breakdown of dead matter and wastes into simple compounds that can be directed back into natural cycles of living things.
- Symbiotic Association
- Symbiosis: partnership between organisms that benefits at least one of them.
- Bacteria and fungi live in complex association with plans that assist the plants in obtaining nutrients and water and may protect them against disease.
- Similar relationships occur with animals like cattle stomachs.
- Flora: microbes that normally inhabit the bodies of animals.
- Serve as barriers to infectious disease.
- Applications Using Microorganisms: Versatile Chemical Machines
- Fermentation: large scale process in industry using microbes as little factories.
- Bioremediation: use of biological agents to remedy environmental problems.
- Conversion of toxic chemicals into harmless chemicals.
- Recombinant DNA: powerful technique for designing new organisms.
- Microbes can be reengineered to synthesize desirable proteins such as drugs, hormones, enzymes, and physiological substances.
- Pathogens: disease causing agents.
- There are more infections than the human population due to people acquiring more than one infection.
- Increase in emerging and reemerging diseases.
- AID, hepatitis C, and viral encephalitis are diseases that cause severe mortality and morbidity.
- Many disease are suspected of having a microbial orgin.
- Diabetes and Coxsakie virus.
- Schizophrenia and a virus called borna agent.
- Emerging Diseases
- Microorganisms have a formidable capacity to respond and adapt to alterations in the individual, community, and environment.
- Common influence for emerging disease:
- Increase in population.
- No vaccination (increase of people at risk).
- Increase resistance to drugs.
- Travelling.
- Drugs, Multiple Partners.
- Change in method of agriculture and technology.
- Large outbreaks due to mass production and tainted resources of production.
- Tainted soil due to fecal matter.
- Escherichia coli 0157:H7 --fresh vegetables, fruits, & meats.
- Cholera bacteria --seafood.
- Salmonella --eggs & milk.
- Protoza such as Cryptosporidium and Giardia. --water supply.
- Flucuations in ecology, climate, animal migration, and human travel.
- Zoonotic Pathogens
- An infection indigineous to animals that can be transmitted to human.
- Many have mutated to become more virulent.
- Top diseases:
- 1. Respiratory Diseases
- 2. AIDS
- 3. Diarrhea
- 4. TB
- 5. Malaria
- 6. Measles
- Epidemic
- Cholera outbreak 1860s
- First time that outbreaks in a population were linked to a diseases.
- Epidemiology used and documented for first time by Dr. Snow.
- Other examples of epidemics: smallpox, influenza (same strain as swine flu), black death, AIDS, & TB (tuberculosis).
- Main causes of death in US:
- Heart Disease
- Cancer
- Stroke (Health Science)
- Cellular Organization
- Prokaryotic Cells
- Generally smaller than eukaryotic cells.
- Lack unique structures such as nucleus and organelles.
- Organelles: small membrane-bound cell structures that perform specific functions in cells.
- Common structures: ribosome, chromosome, cell wall, cell membrane, flagellum.
- Eucaryotic Cells
- Have membrane-bound cell structures and a nucleus.
- Common structures: ribosome, nucleus, mitochondria, flagellum, cell membrane.
- All prokayotes are microogranisms, few eukaryotes are microorganisms.
- Most microorganisms are single cells or a few cells.
- Few animals such as helminth worm and insects are considered microorganism because of their role in disease, even though they can be seen with the naked eye.
- A Note On Viruses
- Viruses have a small amount of hereditary material wrapped up in a protein covering.
- Highly dependent on host cell's machinery for their activities.
- Microbial Dimensions: How Small Is Small?
- Macroscopic organisms: given in centimeters (cm) and meters (m).
- Microorganisms: mostly micrometers (um). Few exemptions are nanometer (nm) and millimeters (mm).
- Helminths are mm.
- Viruses are nm.
- Size range of microbes is from 20 nm to 3-4 mm (protozoans e.g. perimecium & amoebas).
- Lifestyles of Microorganisms
- Parasites: organisms that are harbored and nourished by other living organisms, the host.
- Most microbial parasites are some type of bacterium, fungus, protozoan, worm, or virus.
- Parasites that that cause important disease are only a small percentage.
- The Development of the Microscope
- Hooke
- Studied dead cells and made many observations about the microbiology world.
- Antonie van Leeuwenhoek
- First microscope with clarity came
- Linen merchant and self made microbiologist.
- Leeuwenhoek's original purpose for the microscope was for examining cloth fabric for flaws and later for what he terms animalcules, blood, and tissues.
- Discovered microorganisms.
- Produced microscopes at 300X magnification.
- The Establishment of the Scientific Method
- Development of a experimental system that answered questions objectively and not based on prejudice.
- Scientific Method
- Approach taken to explain certain natural phenomenon.
- Hypothesis: tentative, not certain, explanation to account for what has been observed or measured.
- Inductive Approach
- Accumulates specific data or facts and formulate hypothesis.
- "Are various observed events best explained by this hypothesis or by another one?"
- Deductive Approach
- Constructs hypothesis, tests its validity by outlining particular events that are predicted by the hypothesis, then performs experiments to test for those events.
- "If the hypothesis is valid, then certain specific events can be expected to occur."
- Scientific method is set up to account for consequences for each variable.
- There is also a control group involved with every experiment.
- Test group that is the same as the others, but omits only the variable being tested.
- Theory: a hypothesis that is supported by a growing body of data and survives vigorous scrutiny.
- Spontaneous Generation vs Biogenesis Debate
- Spontaneous generation: belief of the rise of living organisms from non-living or decomposing matter.
- Proposed by Aristotle.
- Biogenesis: life arising from other life of the same kind.
- Cell theory: all organisms are made of cells.
- Francesco Redi Experiment
- Proved maggots were offspring from flies surrounding open meat.
- Disproved abiogenesis.
- Abiogenesis (Jablot vs Needham vs Endospores)
- Abiogenesis: life from inanimate objects.
- Louis Jablot (biogenesis)
- Boiled two containers of liquid and left one seals and the other open.
- Showed that open container exposed the liquid for microorganisms; what was presumed from air-laden dust.
- John Needham (abiogenesis)
- Created similar experiments as Louis Jablot, but he used mutton gravy.
- Contradicted Louis Jablot, but there was it was a result of no knowledge of heat-resistant endospores.
- Endospore: dormant, tough, temporary non-reproductive structure from certain bacteria.
- Shultz & Schwann's Test
- Believed air was the source of microbes so they constructed an experiment where the air was sterilized with heat.
- Community defended abiogenesis claiming the experiment made that system hazardous for spontaneous generation to occur.
- Schroeder & Van Dusch
- Set up similar experiment, but they used cotton to filter the air from the system.
- Louis Pasteur
- Heated flasks and created a bend opening to trap microbes as the flasks were heated. At the bend the microbes were trapped and broth remained sterile. If stem broken off, leaving broth open, growth occurs.
- Law or Principle
- A widely accepted and proven theory.
- The Development of Medical Microbiology
- The Discovery of Spores and Sterilization
- John Tyndall
- Studies provided initial evidence that some microbes have high heat resistance and particular vigorous treatment is required to treat them, Tyndallization.
- Discovered some bacteria existed in two forms.
- Heat stable form (endospore).
- Heat-sensitive form.
- Heat treatment: tyndallization.
- Ferdinand Cohn
- Discovered heat-resistant endospores as the reason heat would sometimes fail to kill all microbes.
- Sterile: completely free of all lifeforms including spores and viruses.
- Development of Aseptic Techniques
- Robert Koch
- Linked microscopic organism with specific disease.
- Experimented with bacteria growth media.
- Culture techniques: used agar (derived from seaweed and added nutrients).
- Proved bacterium caused anthrax.
- Anthrax was caused from Bacillus anthracis.
- Koch's Postulate
- A series of proofs that verified the germ theory and could establish whether an organism was pathogenic and which disease it caused.
- Joseph Lister (Father of Modern Antiseptics)
- Took notice of a report by Semmelwas about mothers were giving birth who were getting infections were possibly getting infections from doctors coming from the autopsy room to the examinations in an Australia.
- Introduced aseptic techniques to reduce microbes in medical setting.
- Had surgeons use phenol, carbolic acid.
- Dramatically reduced gangrene.
- Major advance in infection control and modern surgery.
- The Discovery of Pathogens and Germ Theory of Disease
- Germ Theory of Disease
- Diseases could arise from infection.
- The Beginnings of Immunology
- Edward Jenning (1790)
- Milkmaid claimed she couldn't get smallpox because she had cowpox before.
- Beginning of vaccination (vacca = cow).
- Paul Ehrlich
- Developed a synthetic arsenic drug Salvarsan to treat syphilis.
- Alexander Fleming
- Discovered lysozyme in tears, saliva, and other natural substances.
- First body secretion shown to have chemotherapy properties.
- Discovered the first antibiotic by observing penicillum fungus.
- Sulfonamides were synthesized in 1930.
- Nomenclature: system of naming.
- Taxonomy: formal system of organizing, classifying, and naming living things.
- Initiated by Von Linne.
- Taxa: basic rules for taxonomic categories.
- Levels of Classification
- Levels from top: domain, kingdom, phylum, class, order family, genus, species.
- Species
- Successfully reproduce with fertile offspring with a common set of characteristics.
- Sub-Species
- Biovars: difference observed in growth, etc.
- Pathovars: differences in the patient symptoms/signs.
- Serovars: differences detected by immunological antibody.
- Assigning Specific Names
- Common names are sometimes given by features of the organism.
- Scientific name: bionomial system of nomenclature.
- Genus + species: Saccharomyces cerevisiae.
- Origin and Evolution of Microorganisms
- Evolution: living things change gradually through hundreds of million years and these evolvements are expressed in various types of structural and functional changes through many generations.
- Systems of Presenting a Universal Tree of Life
- Five basic kingdoms: prokaryotae (monera), protista, myceteae (fungi), plantae, and animalia.
- Procaryotes
- Procayoate (Monera) <--Kingdom
- Bacteria: typical prokaryotic cell structure.
- Archeae: cells with atypical cell structure that live in extreme environments.
- Domain Eukarya
- Protista (protists)
- Mostly single-celled.
- Lack more complex levels of organization, such as tissues.
- Algae.
- Protozoans
- Animal-like creatures that eat other live or dead organisms.
- Mycetae (Fungus)
- single- multicelled eucaryotes that are encased in cell walls and absorb nurtients from other organisms.
- Exception from infectious worms and anthropods.
- Helminths (Parasitic Worms)
- Animalia and Plantae
- Generally not included in the study of microbiology due to being larger.
- Multicellucar.
Reference: https://sites.google.com/site/rccmicrobiology/chapter-1-the-main-themes-in-microbiology