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microbiology
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Chapter 1Chapter 1
Microorganisms and Microorganisms and MicrobiologyMicrobiology
OUTLINEOUTLINE
• Introduction to MicrobiologyIntroduction to Microbiology
Science of MicrobiologyScience of Microbiology
Microbial CellsMicrobial Cells
Microbial CommunityMicrobial Community
Evolution and the Extent of Microbial LifeEvolution and the Extent of Microbial Life
Impacts of Microorganisms on HumanImpacts of Microorganisms on Human
• Discovery Pathways in MicrobiologyDiscovery Pathways in Microbiology
Introduction to MicrobiologyIntroduction to Microbiology
Science of Microbiology
1. Understanding basic life processes Microbes are excellent models for understanding cellular processes in unicellular and multicellular organisms
2. Applying that knowledge to the benefit of humans Microbes play important roles in medicine, agriculture and industry
I. Properties of all cells
Metabolism Growth Evolution
Cell
Environment
Ancestralcell
Distinct species
Distinct species
Fig 1.3
All Microbial Cells Share the Following
II. Properties of some cells
Motility Differentiation Communication
Spore
Fig 1.3
Some Microbial Cells Display the Following
Fig 1.4
All Microbial Cells Coordinate Catalytic and Genetic functions
Microorganisms and Their Environments
In nature, microbial cells live in populations with other species.
Microbial communityMicrobial ecosystemMicrobial ecology
Fig 1.5
Small lake Sewage sludge
Purple sulfur bacteria bloomin a small lake
Evolution and the Extent of Microbial Life
The First Cells and the Onset of Biological EvolutionLUCA (last universal common ancestor)
First cells were all microorganisms
Life on Earth through the AgesAnaerobic microorganisms
Cyanobacteria (generated O2)
Multicellular life forms
The Extent of Microbial LifeTotal microbial cell numbers = 2.5 × 1030
Most cells are in the oceanic and terrestrial subsurface
Fig 1.6
Summary of Life on Earth through Time
Distribution of Microorganisms in and on Earth
Impact of Microorganisms on Humans
• Microorganisms as Agents of Disease• Microorganisms, Digestive Processes and Agriculture
Nitrogen-fixing bacteria
Cellulose-degrading microbes in the rumen
• Microorganisms and FoodFermentation and Food spoilage
• Microorganisms and Energy H2, ethanol and methane (biofuel)
• Microorganisms and EnvironmentBioremediation
• Microorganisms and Their Genetic Resources Biotechnology
Fig 1.8
Microbiologists’ Success in Preventing Infectious Diseases
United States
Fig 1.9
Impacts of Microorganisms on Agriculture
Fig 1.11
Ethanol plantNatural gas (methane)
Microorganisms for Biofuels
Pathways of DiscoveryPathways of Discovery
in Microbiologyin Microbiology
Historical Roots of Microbiology
Microbiology began with the microscope
•Robert Hooke (1635–1703): the first to describe microbes: fungi fruiting bodies.•Antoni van Leeuwenhoek (1632–1723): the first to describe bacteria. •Ferdinand Cohn (1828–1898):
1. discovered endospores in Bacillus
2. initiated bacterial classification3. founded a scientific journal4. devised the use of cotton for closing flasks and tubes
Fig 1.12
Robert Hooke (1635–1703)
Bellows
LensMold structures
on the surface of leather
Lens
Fig 1.13
Antoni van Leeuwenhoek (1632–1723)
His microscope
His drawings
Human blood smearthrough his microscope
Main Biological Questions in the Mid- and Late Nineteenth Century
1. Does spontaneous generation occur?
2. What is the nature of infectious disease?
Louis Pasteur (1822-1895)
• Disproved theory of spontaneous generation
•Led to the development of methods for controlling the growth of microorganisms (aseptic technique)
Steam, forcedout open end
Nonsterile liquidpoured into flask
Neck of flaskdrawn out in flame
Liquid sterilizedby extensive heating
Fig 1.16a
Dust and microorganismstrapped in bend Open end
Liquid cooledslowly
Liquid remainssterile indefinitely
Long time
Fig 1.16b
Flask tipped somicroorganism-laden dustcontacts sterile liquid
Liquid putrefies
Short time
Fig 1.16c
• Discovered that living organisms discriminate between optical isomers.
• Discovered that alcoholic fermentation was a biologically mediated process (originally thought to be purely chemical).
• Developed vaccines for anthrax, fowl cholera, and rabies.
Louis Pasteur (1822–1895)
Robert Koch (1843–1910)
• Demonstrated the link between microbes and infectious diseases.
Koch’s postulates
• Identified causative agents of anthrax and tuberculosis.
Fig 1.19
KOCH’s Postulates
• Discovered that using solid media provided a simple way of obtaining pure cultures:
Potato slicesGelatinAgar
Robert Koch (1843–1910)
Rise of Microbial Diversity
Martinus Beijerinck (1851–1931) • Developed enrichment culture technique(Microbes isolated from natural samples in a highly selective fashion by manipulating nutrient and incubation conditions)
Sergei Winogradsky (1856–1953)•Coined the concept of Chemolithotrophy(Oxidation of inorganic compounds linked to energy conservation)
•Demonstrated that specific bacteria are linked to specific biogeochemical transformations (e.g., S & N cycles)
Modern Era of Microbiology
• In the 20th century, microbiology developed in two distinct directions: Applied and Basic.
Subdisciplines of Microbiology
Led to systematic, technology-driven research:
•Genomics: study of entire genome•Transcriptomics: study of RNA patterns•Proteomics: study of all the proteins produced by cell(s)•Metabolomics: study of metabolic expression in cells
Genomics Revolution
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