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 engineering

UN 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