Intro to Microbiology A Brief History of Microbiology The Microbes of Microbiology Updated 1/2011.
Introduction to Microbiology · 2016-11-20 · Microbiology Microbiology is the study of...
Transcript of Introduction to Microbiology · 2016-11-20 · Microbiology Microbiology is the study of...
Microbiology Microbiology is the study of microscopic organisms, referred to as microorganisms (microbes) - a diverse lot!
viruses
Microbiology
All microbes share the common characteristics of relatively rapid growth, ubiquitous distribution and smallness.
Single microbes are not visible to the naked human eye but are sometimes visible as colonies, consisting of groups of millions to billions individual microbes.
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Microorganisms are ubiquitous
Microorganisms are ubiquitous
Microorganisms are ubiquitous
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Microorganisms are ubiquitous
Microorganisms establish associations with other organisms
Bacteria are required for fermentation of sugars in ruminant animals
Bacteria are often associated with plant
roots
Microorganisms established associations with other organisms
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Microorganisms established associations with other organisms
Scleractinian corals contain symbiotic dinoflagellate algae (zooxanthallae) inside their tissues
Microorganisms establish associations with other organisms that may be
Beneficial
Eg. Rhizobacteria associated with soybean plant roots Bacteria fix nitrogen that can then be used by the plant
Microorganisms establish associations with other organisms that may be
Harmful
Cotton diseased seedlings
Cotton Healthy seedlings
The fungal pathogen
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The importance of microbes The Importance of Microorganisms Oldest form of life Largest mass of living material on Earth Carry out major processes for
biogeochemical cycles Can live in places unsuitable for other
organisms Other life forms require microbes to survive
The scope of Microbiology Microbiology covers both basic and
applied sciences:
1. understanding basic life processes of microbes and other organisms (model organisms)
2. application of the basic knowledge for the benefit of humankind and the environment
Microbes as model organisms Some advantages of using microorganisms as
model systems include:
1. Relatively simple organisation
2. Easy to grow, both small and large scale
3. Well-established, relatively simple genetic system
4. Availability of a large number of mutants for genetic studies
5. Relatively easy to manipulative biochemically and genetically
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Microbes as model organisms Escherichia coli (prokaryotic - bacteria, human
intestine)
Saccharomyces cerevisiae (eukaryotic, baker’s yeast)
Applied Microbiology Medical Microbiology e.g. pathology, epidemiology,
immunology Agricultural Microbiology e.g. soil microbiology, plant-
microbe interactions, rumen microbes Food Microbiology e.g. dairy products, baking, brewing,
fermented foods Industrial Microbiology e.g. fermentation, antibiotics,
enzymes, chemicals
Environmental Microbiology e.g. removal of toxic wastes, sewage treatment, water quality
Biotechnology e.g. vaccines (hepatitis B), gene technology (growth hormone, insulin)
Basic concepts in Microbiology Like all organisms, the cell is the fundamental unit of
microbial life. What is the exception?
The Cell: Cytoplasmic (cell) membrane Barrier that separates the inside of the cell from the
outside environment Cell wall Present in most microbes, confers structural strength
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Basic concepts in Microbiology Characteristics of microbial systems Metabolism: chemical transformation of nutrients Reproduction: generation of two cells from one Evolution: genetic changes in cells that are
transferred to offspring Differentiation: synthesis of new substances or
structures that modify the cell (only in some microbes?) Communication: generation of, and response to,
chemical signals (only in some microbes?) Movement: via self-propulsion, many forms in
microbes
Cellular properties
Basic concepts in Microbiology Microbial Growth is the increase in cell number of a
microbial species. Growth requires:
1) supply of energy and precursors by the catalytic machinery for the biosynthesis of all cell component and
2) the entire complement of genes (the genome) to replicates.
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Microbial environments Microbial ecosystems (e.g. marine ecosystem,
terrestrial ecosystem) consist of all of the living organisms together with the physical and chemical components of their environments
Microbial communities consist of various microbial populations
Each population is a group of cells derived from a single parental cell interacting in their immediate environment, called their habitat
Microbial environments
Microbial populations may interact with each other in beneficial, neutral or harmful ways
Environmental conditions (food resources, temperature, pH, oxygen etc) and microbial interactions will determine the diversity and abundance of microbial populations in their habitat
In return, ecosystems are greatly influenced by microbial activities, which change the physical and chemical properties of the habitat.
Life on Earth through the Ages
- Earth is 4.6 billion years old
- First cells appeared between 3.8 and 3.9 billion years ago
- The 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
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Major microbial groups Bacteria, Archaea and Eukarya
The recent phylogenetic tree of life is based on molecular analysis (sequence comparison) of the ribosomal RNA genes of organisms
16S-rRNA for Bacteria & Archaea, 18S-rRNA for Eucarya
The tree shows three domains of organisms: Bacteria, Archaea and Eukarya
Last universal common ancestor (LUCA)
Microbial groups
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Microbial Group Size General characteristics
Bacteria 0.2-2µm Prokaryotic, unicellular, asexual reproduction
Virus 0.015-0.2 µm Obligate parasite, require living cells
Yeast 5-10µm Eukaryotic, unicellular, asexual/sexual reproduction
Fungi 2-10µm by several mm
Eukaryotic, multicellular, asexual/sexual reproduction
Protozoa 2-200µm Eukaryotic, unicellular, asexual/sexual reproduction
Algae 1µm by several cm
Eukaryotic, unicellular/multicellular, photosynthetic, asexual/sexual reproduction
Microorganisms impact on human life
• Microorganisms can be both beneficial and harmful to humans
• Emphasis is typically placed on harmful microorganisms (infectious disease agents, or pathogens)
• Many more microorganisms are beneficial than are harmful
• We will cover examples of both
Microorganisms as disease agents Control of infectious disease during last century
Microorganisms impact on human life
Microorganisms and Agriculture Many aspects of agriculture depend on microbial
activities Positive impacts nitrogen-fixing bacteria cellulose-degrading microbes in the rumen regeneration of nutrients in soil and water
Negative impacts diseases in plants and animals
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Microorganisms impact on human life
Microorganisms and Food Negative impacts Food spoilage by microorganisms requires
specialized preservation of many foods Positive impacts Microbial transformations (typically
fermentations) yield: dairy products (e.g., cheeses, yogurt,
buttermilk) other food products (e.g., sauerkraut,
pickles, leavened breads, beer)
Microorganisms impact on human life
Microorganisms, Energy, and the Environment The role of microbes in biofuels production For example, methane, ethanol, hydrogen
The role of microbes in cleaning up pollutants (bioremediation)
Bugs feed on pollutants
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Microorganisms impact on human life
Microorganisms and Their Genetic Resources Exploitation of microbes for production of
antibiotics, enzymes, and various chemicals Genetic engineering of microbes to generate
products of value to humans, such as insulin (biotechnology)
Microbiology as a Career Clinical medicine Research and development – pharmaceutical,
chemical/biochemical, biotechnology Microbial monitoring in food and beverage
industries, public health, government
The role of the infinitely small in nature is infinitely
large” – Louis Pasteur
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