Microbial World

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22 Φεβ 2013 (πριν από 4 χρόνια και 3 μήνες)

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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


parasitology


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 body

Microbes


Lactobacillius

acidophilus

make

yogurt

Others 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


Phylogenetics

= ________


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

S
pontaneous 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