Introduction to Microbiology

• Microbiology is the study of … • Microorganisms: all microscopic cellular organisms and include the viruses, which are microscopic but not cellular microorganisms... - Microbial cell

Introduction to Microbiology

Instructor: Pham The Hai

What is Microbiology?

• Microbiology is the study of …

• Microorganisms:

all microscopic cellular organisms and

include the viruses, which are microscopic but not cellular

microorganisms

The size of a microbial cell

What is Microbiology?

• Microbiology is the study of

microorganisms but what is it all about?

- Microbial cells and how they work

- Diversity and evolution of microbial cells

- What impacts microbes do to the

environment: in soil, water, animals, plants and human

 Microbiology is the most fundamental

biological science

What is Microbiology?

• Microbiology:

As a basic science: understanding the living

world of microscopic organisms ->

chemical/physical basis of life (why?)

As an applied science: at the center of many

important aspects of human and veterinary medicine (infectious diseases), agriculture (soil fertility), and industry (antibiotics,

proteins, food, etc.)

The role of microorganisms

smallest forms of life, but

• constitute the bulk of biomass on Earth

• carry out many necessary chemical

reactions for higher organisms

• play vital role in cycles of material

The world cannot exist without microbes!

How do microbial cells look

like?

What are properties of cellular life?

• Cells as

Biochemical Catalysts:

Cells contain enzymes

• and as

Genetic

Entities:

Cells contain genes

Microorganisms and Their Environments

• In nature, microbial cells live in populations

• Habitat: the environment the population lives

in

• Microbial community: consists of different

microbial populations interacting with each other

• A microbial community + its habitat  an

ecosystem

 The study of interactions of microbes with other organisms and the whole ecosystem: microbial ecology

Microbial communities

Evolution and the Extent

of Microbial Life

Why did cyanobacteria appear so early?

Evolution and the Extent

The Extent of Microbial Life

• Microbial life is all around us!

even in hot springs, glacial ice,

10km under earth surface

• Total number of microbial cells on earth:

The Extent of Microbial Life

Microorganisms and Humans

• Basic understanding on microbes 

applications to benefit humans!

Microorganisms as Agents of

Disease

• Many microbes = pathogens

• Understand how pathogenic microbes

work  control infectious diseases

• New threats:

bird or swine flu, or Ebola hemorrhagic fever

Microorganisms and Agriculture

-Nodule bacteria:

nitrogen-fixers

- Rumen bacteria:

the digestion-aids

Microorganisms and Food, Energy, and the Environment

• Prevention of food spoilage; food safety

• Food production: yeast as bakers,

History of Microbiology

In 1665, Robert Hooke (Englishman) reported that living things were composed of little

boxes or cells

Chapter 1 Introduction

History of Microbiology

1673-1723, Antoni van Leeuwenhoek (Dutch) described live

microorganisms that

he observed in teeth scrapings, rain water, and peppercorn

infusions

Tiny beaties (bacteria)

Blood cells

Leeuwenhoek (1684)

Opposite: living cells can

arise only from preexisting

cells – biogenesis (Rudolf

Virchow (German))

Many believed in spontaneous generation :

life can arise from non-living matter

In 1668, Francesco Redi (Italian)’s

experiment:

From where did the maggots come?

What was the purpose of the sealed jars?

Spontaneous generation or biogenesis?

Can you think of an experiment that could

disprove spontaneous generation?

Spallanzani’s experiment

1860s: Pasteur’s experiment 

spontaneous generation

or biogenesis?

The Golden Age of Microbiology

1857-1914

Beginning with Pasteur’s work,

discoveries included the relationship between microbes and diseases,

immunity, and antimicrobial drugs

Pasteur’s contributions (cont.)

• Vaccines

Rabies, anthrax, …

• Pasteur’s work helps solidify the germ

theory of disease

The Germ Theory of Disease

1835: Agostino Bassi : a silkworm disease was caused by a fungus

1840s: Ignaz Semmelwise: handwashing  prevent transmission of puerperal fever

from one patient to another

1860s: Joseph Lister proposition after

looking at Pasteur’s work: chemical

disinfectants  prevent surgical wound

infections

The Germ Theory of Disease

theory of diseases:

a bacterium

causes anthrax

Fundamentals of infectious diseases !!!

Pure culture, solid media

- The birth of microbial systematics

Koch:

• A suspected pathogen must be isolated and grown away from other microorganisms

 a pure culture

• To obtain pure cultures  use solid media

Koch first used glass boxes + gelatin

Walter Hesse  proposed to use agar (solid at 37C, melting at 45C) to replace gelatin

Richard Petri  Petri dishes (stackable, easier for

autoclaving, better to prevent contamination)

instead of glass boxes

Pure culture, solid media

- The birth of microbial systematics

Koch’s glass box Petri dish

Figure 2 Photo of a Petri

dish containing colonies of

marine bacteria

“All bacteria which maintain the characteristics which differentiate one from another when they are cultured on the same medium and under the same conditions, should be designated as species, varieties, forms, or other suitable

designation.” – Robert Koch

The establishment of microbial systematics

Martinus Beijerinck and the Enrichment Culture Technique

• Enrichment: using highly selective techniques

of adjusting nutrient and incubation conditions

 favor a particular metabolic group of

organisms

Azotobacter enriched and

isolated by Beijerinck (1900)

Alexander Fleming

• 1929 Discovered penicillin

(the first known antibiotic)

The Modern Era of Microbiology

• 20th century: microbiology became one of the major biological sciences

• 2 directions:

Discovery (basic)

Problem-solving (applied)

* Various subdisciplines

The Modern Era of Microbiology

• Microbial genetics  “Modern biology”

Driven by: Molecular biology

E coli genome

A metagenomic analysis

On Funny Green Squares

Basic techniques

in Microbiology

Why do you need to know

clearly about basic techniques

in Microbiology ?

• Difficult to see and to work with microbes

• Wrong practices  wrong work results

• Safety reasons <- work with pathogens

Green algae

Purple phototrophic bacteria

Simple stain

• Basic techniques in Microbiology:

Light Microscopy, Culture media – pure

culture, Staining

Maybe U!

Seminar topic next week

• Cell structure and evolutionary history

(seminar topic 1)

Information sources:

- Brock Biology of Microorganisms (pp 31-34)

- Any other sources you can use

• Microbial diversity (topic 2)

Information sources:

- Brock Biology of Microorganisms (pp 36-43)

- Any other sources you can use