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