Unit E
Microbiology in Agriscience and
Production Agriculture
Objective 11.00
What is a virus?
• A virus is an organism composed of a DNA or
RNA core surrounded by a tough protein
outer coat.
– NOT CLASSIFIED AS A TRUE LIVING
ORGANISM
– Cannot reproduce sexually, only through division
in a HOST (viruses are parasitic)
– Reproduce quickly, mutate often, and can survive
harsh environmental conditions
Viruses
• Responsible for
some of the most
dangerous human
ailments
• Can be destroyed
by altering DNA
• Human
Immunodeficiency
Virus
HIV Virus
Viruses
• Often used as a vector to transport genes
into organisms when genetically modifying
organisms.
Types of Viruses
• Tobacco Mosaic Virus (TMV)-often used as a
vector for genetic engineering in plants-1
long RNA molecule
• Bacteriophage-DNA packaged tightly in a
protein head-often used in genetic
engineering
Types of Viruses
• Common viruses
–
–
–
–
–
–
–
Human Immunodeficiency Virus(HIV)
Influenza
Common Cold
Measles
Norwalk
Hepatitis
Rabies
Measles
Prokaryotic Organisms
What is a prokaryotic organism?
• A single celled organism
that has no membrane
bound organelles and no
distinct nucleus.
• Usually have very short
life spans
Characteristics of Prokaryotic
Organisms
• Contain free-floating DNA
• Can be autotrophic (produce their own
energy) or heterotrophic (consume other
things for energy)
• Also reproduce quickly and mutate often, but
are not as tough as viruses
Examples of Prokaryotic
Organisms
• Bacteria
• Cyanobacteria
• Blue-green algae
Blue-green Algae
Bacteria
Characteristics of Bacteria
• Can be beneficial or harmful to humans
• Unlike viruses, bacteria are not PARASITES,
and do not need a host
• Molds and fungi including yeast are not
bacteria
Beneficial Bacteria
• Provide a benefit to human activity through
normal function or manipulation through
biotechnology techniques
• Examples:
– Nitrobactus alkalikus
– Lactobaccillius sp.
Nitrobactus alkalikus
• Bacteria occurring naturally in soil on the roots
of legumes, that change nitrogen in the air to a
form useful for plants
– Nitrogen fixing
Lactobaccillus sp.
• A genus of microorganisms that have been
introduced to foods (often dairy products) to
aid in digestion
Harmful Bacteria
• Affect agriscience products and processes in
a negative manner, affecting both plants and
animals
• Example:
–
–
–
–
Eescherichia coli (E. coli)
Clostridium botulinum
Salmonella enteriditis
Pythium spp.
Destroying Harmful Bacteria
• Sterilization-kills all living organisms in a or
on a substance
• Pasteurization-kills most harmful
microorganisms, leaving some beneficial
organisms surviving
Multiform Bacteria
• Can either be beneficial or harmful to plants
under different circumstances and conditions
• Example:
– Agrobacterium tumefaciens-naturally occurring
bacteria that penetrates plant cells transmitting its
own DNA to the cells and causing the growth of a
gall (tumor like mass)
• Used in genetic engineering to transmit genes
Agriscience Uses of Bacteria
•
•
•
•
Pharming
Bioremediation
Biocontrol
Biofuels
Example of Pharming
• Inclusion of
cholesterol
consuming
bacteria in milk
products to lower
human
cholesterol
Bioremediation
• Use of bacteria that consume contaminants
in soil and water
– Example- bacteria used to “eat” oil from tanker
spills, or excess organic nutrients from animal
waste
Biocontrol
• Use of beneficial bacteria in horticulture to kill
harmful bacteria in soil, water and on plant
surfaces.
Biofuels
• Very few applications in renewable energy or
biofuels now, but lots of potential applications
Eukaryotic Cells
What is a Eukaryotic Cell?
• Advanced cells characterized by the
presence of membrane bound organelles
and a distinct nucleus.
– Usually occur in multicellular organisms, but also
include a few single celled Protists.
Eukaryotic Cell Structures
•
•
•
•
•
•
Cell membrane
Golgi apparatus
Mitochondria
Nucleus
Ribosomes
Vacuoles
Cell Membrane
• Selectively permeable
membrane surrounding all
eukaryotic cells.
• Protects the cell and controls the
movement of substances into
and out of the cell.
Golgi Apparatus
• Center for the distribution
of proteins, enzymes, and
other materials through
the cell
– Like the post office
Mitochondria
• Structures inside the cell that convert simple
sugars to a useful form of cellular energy
through the process of respiration
Nucleus
• A large central segment of the eukaryotic cell
that contains the cell’s genetic information
(DNA)
Ribosomes
• Small structures in
the cytoplasm of the
cell that utilize RNA
to produce proteins
for cell functions
Vacuoles
• Specialized
“bubbles” in cells
used for storage,
digestion, and
excretion.
• Much larger in plant
cells
Special Plant Cell Structures
• Chloroplasts-use chlorophyll to capture light
energy for conversion to chemical energy
• Cell wall-structure outside the cell membrane
that helps support and protect cells.
– Not semi-permeable
Specialized Eukaryotic Cells
• Diploid Cells
• Haploid Cells
• Stem Cells
Diploid Cells
• Includes all single celled eukaryotes and
every non-reproductive cell in multicellular
eukaryotes (plants and animals)
– Examples: Skin cells, muscle cells, nerve cells
Haploid Cells
• Specialized reproductive cells in eukaryotes
that contain ½ the amount of genetic material
of normal (diploid) cells
– Also called gametes or sex cells
– Haploid cells combine during sexual reproduction
to create a fertilized egg
– 4 distinct types
• Male-sperm or pollen
• Female-egg or ovum
Stem Cells
• Produced from the union of
haploid cells
• Special cells that differentiate
into all diploid cells in the
body.
Culturing Bacteria
Ideal Bacterial Environments
• Most bacteria prefer warm moist
environments, though specific species
require different culturing conditions
• Bacteria thrive in the harshest environments
on earth
– Deep sea ocean vents with no sunlight and little
useable oxygen
Bacteria Testing Methods
• Swabbing-method used to test surfaces for
bacteria
– A sterile cotton swab is dipped in a dilution
solution and rubbed across the surface to be
tested.
– The end of the swab is cut and dropped into the
solution
– The infested solution is swirled at .1 ml extracted
for plating
Plating
• The process of physically spreading bacteria
on an agar based culture media
Plating Process
• To produce agar plates, heat a clear solution
in a water bath. Next, proceed to pour the
solution into Petri dishes and immediately
seal.
• Bacteria can be spread using an inoculating
loop or glass “hockey stick”
• Plates should be sealed and incubated at 30
degrees Celsius to avoid the growth of most
bacteria harmful to humans (35-37 degrees
for Salmonella)
Identifying/Counting Bacteria
• Different agar mixes can be used to culture
specific types of bacteria.
• Gram staining is used to broadly identify
certain types of bacteria.
• Identifying individual strains is much more
difficult.
Cleanup After Culture of
Biological Labs
Cleanup of Labs
• Cultures should be placed in a biohazard bag
for sterilization in an autoclave set at 121
degrees Celsius and 15 pounds per square
inch (psi) for 15 minutes.
• Agar should be disposed of according to lab
protocol-not poured down sinks, as liquid
agar can quickly solidify and clog drains.
Cleanup of Labs
• Individuals should always wear latex gloves
and immediately dispose of them after use.
• This is due to the hands being the most
common point of contact.
Quiz
•
•
•
•
1. Describe a virus
2. Describe a bacteria
3. Name two Legumes (nitrogen fixing plants)
4. What is the difference in a diploid cell and a
haploid cell?
• 5. How can we kill all bacteria, harmful and
beneficial?
• Extra credit.6. What structure is in plant cell walls
that monogastric organisms cannot break down?