Chapter 1 Main Themes of Microbiology
What is Microbiology ?
Microbiology is a study of microorganisms (microbes, germs) and their activities
What is a
microorganism?
An
organism too small to be seen without a microscope (Smaller than 0.5 mm)
(Bacteria, Fungi, Protozoa, Algae, Viruses)
Branches of Microbiology
Medical Microbiology
Industrial Microbiology
Environmental Microbiology
Agricultural Microbiology
Microbiology is part of some other disciplines
Biotechnology
Food production (Dairy products (yoghurt, cheese), Sauerkraut, Pickles, Sausages, Bread, Beer, Wine, Etc.)
Drug production (penicillin)
Bioremediation detoxification by use of microorganisms
Genetic Engineering (Manipulation of genes of microbes in order to create new products)
The Impact of Microbes on Earth
The first organisms on the planet Earth
Ubiquitous can be found everywhere
Photosynthesis
Oxygen production
Primary production
Synthesis of organic mater
Decomposition
The Impact of Microorganisms on Human Health
Microorganisms as disease agents
Microorganisms live inside our bodies,
normal microflora,
pathogenic
Our body resists the invasion of pathogenic microbes by
skin,
mucous membrane,
stomach acid
antimicrobial chemicals - interferons
Introduction of antibiotics changed the rates for the leading causes of death
CELL TYPES
There are two basic cell types:
- Prokaryotic
Bacteria
Archea
- Eukaryotic
Fungi
Protozoa
Algae
(helimints, plants, animals)
Major difference - organization of nuclear structure
۞Viruses
CELLULAR ORGANIZATION IN MICROBES
Prokaryotic
Cell envelope
Nucleoid
Eukaryotic
Cell envelope
Organelles
Nucleus
Viruses
Do not have cellular structure
One type of nucleic acid DNA or RNA
Can reproduce only when inside a host cell - parasite
Microbial Dimensions
Prokaryotic cells: 1-10 mm
Eukaryotic cells: 10-100 mm
Viruses : 10-100 nm
Lifestyle of Microbes
Autotrophs
Heterotrophs
Parasites
Naming and Classifying Microorganisms
Classification of organisms is called Taxonomy
Based on the system introduced by Carl Linnaeus (1735)
Binomial system of nomenclature
Genus: Bacillus Species:Bacillus subtilis
Bacterial taxonomy has relied on phenotypic analysis (Morphology, cell structures, storage products, Gr- staining, biochemical characteristics)
Molecular taxonomy - Nucleic acid analysis
All organisms belong to three groups: The Three Domain System
Bacteria
Archaea
Eukarya
History of Microbiology
Who Started Microbiology?
Antoni van Leeuwenhoek (1673-1723), a Dutch merchant
The first person to see microbes as being ALIVE!
Father of bacteriology.
What Leeuwenhoek Could See?
Different shapes of bacteria
Red blood cells, spermatozoa, plant and animal cells
Magnification of his microscope was 32X
Robert Hookes Microscope Compared to Leeuwenhoeks
Robert Hook introduced the compound microscope (objective lens + ocular lens)
Robert Hook (1665) reported that the smallest biological structural unites were little boxes - cells.
CELL THEORY all living things are composed of cells
Golden Age of Microbiology - 1830-1900
Scientists searched for answers to the following questions:
Is spontaneous generation of microbial life possible?
What causes fermentation?
What causes disease?
How can we prevent infection and disease?
Is Spontaneous Generation of Microbial Life Possible?
Aristotle proposed spontaneous generation living things can arise from non-living matter
Toads and snakes could be born of moist soil
Maggots (the larvae of flies) could arise from corpses
Finally!
Arguments about spontaneous generation resolved by the French scientist Louis Pasteur 1850s
How he really did it?
Pasteurs S-shaped flask kept microbes out but let air in.
Pasteurs discoveries
Performed the most convincing experiments disproving the theory of spontaneous generation
Role of yeast in alcohol fermentation
Devised the process of pasteurization and basis of aseptic techniques
Disease of vine - could be prevented by heating the wine for a short time to a temp.
55-600C
The first preventive treatment for rabies
What Causes Disease?
Pasteur developed germ theory of disease, but had no proof began working on Anthrax, but could not get a pure culture of the disease producing bacterium
1876 Robert Koch
German bacteriologist, studied causative agents of disease and PROVED the Germ Theory of Disease.
Gave the first proof that bacteria cause disease (by isolating the anthrax bacillus in pure culture) - germ theory of disease
Perfected the technique of isolating bacteria in pure culture - solid media -boiled potato
Discovered Mycobacterium tuberculosis - the organism causing the tuberculosis. Tuberculin - substance used for diagnosis of tuberculosis.
Introduced the staining procedure for M. tuberculosis (acid fast staining)
First to stain bacterial smears
Discovered the causative agent of cholera
1905 received the Nobel Prize for Medicine
Kochs postulates - Identify criteria for proving that a specific type of a microorganism causes a specific disease:
1. The microorganism should be constantly present in a diseased animal
2. The microorganism must be cultivated in pure culture
3. When inoculated into a healthy animal, such microorganism should cause characteristic disease symptoms
4. The microorganism should be re-isolated from the experimental animal, and it should have the same characteristics as the original microorganism.
Joseph Lister
Father of modern surgery
Applied antiseptic (carbolic acid) treatment for prevention and care of wound infection
Introduced the procedure of disinfection of operating rooms
Chemotherapy - treatment of disease by using chemical substances
The first antibiotic was discovered by accident
Alexander Fleming 1928 discovered penicillin
Produced by mold: Penicillim chrysogenum
Commercial production started in 1945 in the US
Problems with antibiotics
Can be toxic to humans
Spread of new varieties of resistant microorganisms
Development of techniques that facilitated further progress of microbiology
Pure cultures (clone) is a culture consisting of only one type of microorganisms
Use of Petri dishes
Aseptic techniques
Bacteria as distinct species
Developments of microbiology in the twentieth century
Bacteriology
Study of Bacteria. New species of bacteria are discovered regularly
Mycology
Study of fungi. Fungal infections rising
Parasitology
Study of protozoa and parasitic worms
Immunology
- Study of immunity. Vaccines available for many diseases
Virology
1892 Dimitri Iwanowski, reported on the presence of infectious agents much smaller than bacteria. He discovered the tobacco mosaic virus.
Recombinant DNA technology
Fragments of foreign DNA can be incorporated into bacterial genom
The Establishment of the Scientific Method
Scientific method based on an experimental system
It includes:
1. Observation and description of a phenomenon
2. Formulation of an hypothesis to explain the phenomena
3. Performance of experimental tests (to confirm or disprove the hypothesis).
If supported Hypothesis becomes a theory