Microbes

jamaicanabsorbingBiotechnology

Dec 5, 2012 (4 years and 6 months ago)

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Microbilogy

bacteria

bacteriophage

algae

spirochaetes

protozoa

viruses

cyanobacteria

fungi



Single
-
celled organisms and some
non
-
cellular parasites

What are microbes?

Microbiology

study of organisms too small to
be seen by the naked eye


Microorganisms (mo’s) are able to carry out life
processes of
growth
,
energy generation
, and
reproduction

in a single cell.


Mo’s are unicellular, small and reproduced by
fission (asexually)


99% of the mo’s cannot be cultured in the lab


Specifically, they have the ability to:


grow on different substances


withstand variation in temperature


withstand variation in barometric pressure


withstand osmotic pressure


withstand changes in pH


Microbial ubiquity…


MO’s exist everywhere
! They are in the soil,
water, your skin and hair, your gastrointestinal
tract, and even on or in your food.


Yet we are barely aware that they exist. We
become aware when we become sick, see spoiled
food or damaged goods.


However, the sheer
minority

(much less than
1%) cause disease. Most are
beneficial

to man
and the biosphere of the earth.


They’re (almost) everywhere!
An overview of prokaryotic life


Prokaryotes were the
earliest organisms

on Earth
(>3.5 bya) and evolved alone for 1.5 billion years.


Today, prokaryotes still
dominate

the biosphere.


Their collective biomass outweighs all eukaryotes
combined by at least
tenfold
.


More

prokaryotes inhabit a handful of fertile soil
or the mouth or skin of a human than the total
number of people who have ever lived.

Microbes exist in huge
numbers!


For example, for bacteria


10 times as many microbial cells as human cells
on/in body


10
9
/gram of soil; 10
3
-
10
4

different populations


10
11
/ gram in intestinal tract


10
5
/ml in groundwater


10
4
/ml in ocean


Amazing But True


More bacteria in our bodies
than human cells!


More different types of
bacterial genes in our body
then there are human genes!


“The second human genome
project” (David Relman)

What Microbiologists Do ???


Work in almost every industry
-

from food, agriculture and
pollution control to biotechnology, pharmaceuticals and health,
government agencies and labs, in education as teachers and
researchers.


No one microbiologist can study everything! That's why people
who become microbiologists usually focus on a particular microbe
or research area.




Bacteriologists focus on bacteria.


Virologists specialize in viruses.


Mycologists study fungi.


Epidemiologists track down outbreaks of disease


Immunologists study how the body defends itself against
microbial invaders?


Fields of Microbiology

10

Characteristics of Cells

Eucaryotic cells: animals, plants, fungi, and protists


contain double
-
membrane bound
nucleus
with DNA
chromosomes


contain membrane
-
bound
organelles
that
compartmentalize the cytoplasm

and perform specific
functions

Procaryotic cells: bacteria and archaea


no nucleus or other membrane
-
bound organelles

The size and cell type of microbes


Microbe

Approximate range of
sizes


Cell type


Viruses


0.01
-
0.25
µ
m


Acellular


Bacteria


0.1
-
10
µ
m


Prokaryote


Fungi


2
µ
m
-
>
1m


Eukaryote


Protozoa


2
-
1000
µ
m


Eukaryote


Algae


1
µ
m
-
several meters


Eukaryote

Size of Microbes

Microbes vary in size ranging
from 10
nm

(nanometers) to
100
mu

(micrometers) to the
macroscopic.


Viruses in
nm

= 10
-
9
m

(meter)


Bacteria in
um

= 10
-
6

m


Helminths in
mm

= 10
-
3

m

Relative sizes of microbes

The power of microbe lies in its speedy
growth

Imagine the weight of biomass of
E.coli

after 24 hrs under optimal growth?

Bacteria

Reproduction


Asexual, through binary fission


No true sexual reproduction, since neither



mitosis nor meiosis exist in




prokaryotes


Horizontal transfer of genetic material



Transformation



Transduction



Conjugation

Direct transfer of genetic
material from one
prokaryote to another

B
inary fission

E. coli


DNA

cell wall

Conjugation in
E. coli

Sex pilus

Sex pilus connects cells and

draws them together

Conjugation tube then forms

Kinds of microbes

Non
-
cellular, parasitic molecules


Viruses


Viroids


Prions

Prokaryotes


Domain Bacteria


Domain Archaea

Eukaryotes


Several Kingdoms in Domain Eukarya


Classification of Microbes


Based primarily on

genetic sequence data;

e.g
., small subunit ribosomal
RNA


present in all
organisms


NOTE: “Microbes” and
“Prokaryotes” are not taxonomic
categories

Bacteria

QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.

Prokaryotes


Peptidoglycan cell walls


Binary fission


Ex: Escherichia coli

Cyanobacteria

Archaea


Prokaryotes


Lack peptidoglycan


Live in extreme environments
(extremophiles)

Include:



Methanogens



Extreme halophiles



Extreme thermophiles

Archaebacteria


Algae

QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.

Eukaryotes


Cellulose cell walls


Photosynthetic


Produce molecular oxygen
and organic compounds


Part of food chain

Fungi

QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.

Eukaryotes


Chitin cell walls


Molds and mushrooms
are multicellular


Yeasts are unicellular

Protozoa

QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.

Eukaryotes


Mostly saprobes and
commensals


May be motile by means
of pseudopod, cilia or
flagella

Viruses

QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.

Acellular


Obligate intracellular parasites


Genome consist of DNA or
RNA called Core


Core surrounded by protein
coat called Capsid


Virion may be enclosed in lipid
envelope

Nonliving parasitic molecules

Viruses


Single or double stranded RNA or DNA



with a protein coat


Common cold, Ebola, HIV



HIV

Nonliving parasitic molecules

Viruses


Single or double stranded RNA or DNA



with a protein coat


Common cold, Ebola, HIV



Viroids


Short, single strand of RNA w/o protein coat


Primarily infect plants



Prions


Protein particles w/o genetic material


Kuru, mad cow, chronic wasting disease



Differences between

bacteria and viruses


Viruses


Obligate intracellular
parasites


No ribosomes


DNA or RNA, not both


seen by EM


10
-
100s of genes


Tangled phylogeny


Bacteria


Usually free
-
living, but
can be parasites


Ribosomes


DNA and RNA


seen by LM


100s
-
1000s of genes


Natural phylogeny

Nutritional Patterns