The Microbial World and

You

The Microbial World and You

Microorganisms too small to be seen

with unaided eye

“Germ” rapidly growing cell

What are microbes?

Fungi

(molds,

yeasts)

mycology

Protozoa

parasitolo

gy

Microscopic

algae

phycology

What do they do?

Decompose

organic waste

Producers in the ecosystem

by photosynthesis

Produce industrial chemicals

Ethanol and acetone

Produce fermented foods

vinegar, cheese, and bread

Produce manufacturing

products

(e.g., cellulase) and

treatment (e.g., insulin)

A few are pathogenic,

disease-causing

Microbes everywhere on your bodyMicrobes— Lactobacillius acidophilus —make yogurtOthers make beer and wine— Saccharaomyces cereviceae

The better question might be, “what don’t they do?”

Allows humans to

Prevent food spoilage

Prevent disease

occurrence

Led to aseptic techniques

to prevent contamination

in medicine and in

microbiology laboratories

Bacteria causes body odor

Bacteria, tiny as they are, can get sick, too!

Under the right conditions a bacterium like Escherichia coli can grow from just one cell to 1 million cells in less than 7 hours!

How their size compares?

Did you know?

How are microbes named and classified?

Linnaeus

established system of scientific

nomenclature.

Each organism has

two names: genus and specific

epithet.

Are italicized or

underlined. The genus

is capitalized and the

specific epithet is lower

case.

Are “Latinized” and

used worldwide.

May be descriptive or

honor a scientist.

Scientific Names

Staphylococcus aureus

Describes the clustered arrangement of the

cells (staphylo-) and the golden color of the

colonies

(aur-).

Escherichia coli

Honors the discoverer, Theodor Escherich,

and describes the bacterium’s habitat–the

large intestine or colon

Taxonomy

What is systematics?

Study of phylogenetic relationships Phylogenetic

s = ________ Taxonomy =

__________

Also a way of organizing/ classifying Taxa (taxon

—singular)

Plant and Animal Kingdoms

Bacteria and fungi

put in the Plant Kingdom

Kingdom Protista proposed

for bacteria, protozoa, algae, and fungi

Prokaryote introduced for cells "without a nucleus“

Prokaryote defined as cells in which nucleoplasm is

not surrounded by a nuclear membrane

Kingdom Fungi

Kingdom Prokaryotae proposed

Two types of prokaryotic cells found

Look at the background!

How are prokaryotes classified?

Use Bergey’s

Manual of

Systemic

Bacteriology

Divides

prokaryotes into

(based on rRNA

sequences)

Bacteria

Archaea

Who is Carl Woese?

1978: created current classification scheme

Three domains

Bacteria

Archaea

Eukarya

Protists

Fungi

Plants

Animals

What are the key differences between the three divisions?

Eukaryotes

Prokaryotes

Archaea

Cell type

Cell wall

Organelles/ nucleus?

Sensitive to antibiotic?

What is the taxonomy of organisms?

Domain

Kingdom

Phylum

Class

Order

Family

Genus

Species

How are eukaryotes classified?

Endosymbiotic

theory

Numerous

kingdoms,

including

Protista

Fungi

Plantae

Animalia

What about viruses—How are they classified?

Not included in three domains, which

are _______ _______ and ______

Why not?

Viral species: population of viruses with

similar characteristics

How do I tell prokaryotes apart?

Really difficult

Morphology is very similar!

B. anthracis B. japonicum

So how can we tell them apart?

Lab techniques

such as

Staining

Gram positive

vs. Gram

negative

Biochemical test Different bacteria

will grow on different types of media

Carbohydrates Proteins

Serology Slide agglutination

test Look for clumping

of bacteria with antiserum

Serotypes are strains with different antigens

DNA fingerprinting

rRNA sequencing

So how can we tell them apart?

A closer look at the microbes

What are bacteria? Simple, single-

celled ubiquitous

Prokaryotes DNA is not

inside a membrane

Come in different shapes Coccus (cocci,

plural) Bacillus

(bacilli, plural) Spiral

(corkscrew, comma or curved)

Peptidoglycan cell wall

Binary fission Some have

flagella

What are archaea?

Also prokaryotes

Cells wall do not have peptidoglycan

Live in extreme conditions

Extreme halophiles

Hyperthermophiles

Methanogens

Not pathogenic

Figure 4.5b

What are fungi?

Eukaryotes Have a true nucleus More closely related to

__________ wall of chitin Uni- and multicellular Includes

Molds Mushrooms Yeasts Slime molds

Sexual and asexual reproduction

Figure 1.1b

What are protozoa?

Eukaryotes

Absorb or ingest

organic chemicals

May be motile via

pseudopods, cilia,

or flagella

Figure 1.1c

What are algae?

Eukaryotes

Cellulose cell walls

Use photosynthesis for

energy

Produce molecular

oxygen and organic

compounds

Figure 1.1d

What are viruses?

Acellular

Consist of DNA or RNA

core

Core is surrounded by a

protein coat.

Coat may be enclosed in

a lipid envelope.

Viruses are replicated

only when they are in a

living host cell.Figure 1.1e

What are multicellular animal parasites?

Eukaryote

Multicellular animals

Parasitic flatworms and round worms are

called helminths.

Microscopic stages in life cycles.

Figure 12.28a

Brief History of Microbiology

The First Observations

Ancestors of bacteria were

first life on Earth.

observed in 1673.

1665, Robert Hooke reported

living things were composed of little boxes or

cells.

1858, Rudolf Virchow

cells arise from preexisting cells.

Cell theory: All living things are composed of

cells and come from preexisting cells.

How did we discover microbes?

Before the microscope: Spontaneous generation “vital force” forms life.

Microscope Van Leeuwenhoeke, 1670s

Louis Pasteur, 1861 Showed microorganisms are in the air

Refutes spontaneous generation with biogenesis Used curved flask

Conditions Results

Nutrient broth placed in flask,

heated, not sealed

Microbial growth

Nutrient broth placed in flask,

heated, then sealed

No microbial growth

Spontaneous generation or biogenesis?

When was the golden age of microbiology? 1857-1914 Pasteurization

Developed after investigation of fermentation

Demonstration of aseptic technique

microbes are responsible for fermentation.

Fermentation

conversion of sugar to alcohol to make beer and wine.

Microbial growth

responsible for spoilage of food.

Pasteur demonstrated

spoilage bacteria killed by heat

Pasteruization

high heat for a short time.

The Germ Theory of Disease

Joseph Lister, 1860s used a chemical disinfectant to prevent surgical wound infections

Germ theory of disease Robert Koch, 1876, Germany Bacillus anthracis causes anthrax provided the experimental steps

Vaccination Edward Jenner, 1796 Small pox and cow pox Immunology

What about modern microbiology?

1928: Alexander Fleming

first antibiotic.

Penicillium fungus made

antibiotic, penicillin,

that killed S. aureus.

1940s: Penicillin was

tested clinically and

mass produced.

Figure 1.5

Some terms in microbiology

Bacteriology is the study of bacteria.

Mycology is the study of fungi.

Parasitology is the study of protozoa and

parasitic worms.

Immunology is the study of immunity. Vaccines

and interferons are being investigated to

prevent and cure viral diseases

Virology is the study of viruses.

Some modern concepts

Bioremediation

degrade organic

matter in sewage.

degrade or detoxify

pollutants such as oil

and mercury.

Biological Insecticides

Biotechnology

Genetic engineeringUN 2.1

What is normal microbiota?

Normal microbiota prevent growth of

pathogens.

Normal microbiota produce growth factors such

as folic acid and vitamin K.

Resistance is the ability of the body to ward off

disease.

Resistance factors include skin, stomach acid,

and antimicrobial chemicals.

What are infectious diseases?

When a pathogen overcomes the host’s

resistance, disease results.

Emerging infectious diseases (EID): New

diseases and diseases increasing in incidence.

West Nile Virus Bovine spongiform encephalopathy Ebola hemorrhagic fever Hantavirus AIDS Anthrax