Microbiology in Agriscience and

Production Agriculture11.01: Explain the difference between viruses

and prokaryotic organisms in order to distinguish characteristics of life.

1. Definition- organism composed of a DNA or RNA core surrounded by a tough protein outer coat.◦ a. NOT CLASSIFIED AS TRUE LIVING ORGANISMS◦ b. Cannot reproduce sexually, only through

division in a HOST (viruses are parasitic).◦ c. Reproduce quickly, mutate often, and can

survive harsh environmental conditions.

Viruses

Why are viruses considered “Nonliving”◦ Viruses, like bacteria, are microscopic and cause

human diseases. But unlike bacteria, viruses are acellular particles

(meaning they aren't made up of living cells like plants and animals are), consisting instead of a central core of either DNA or RNA surrounded by a coating of protein.

◦ Viruses also lack the properties of living things: They have no energy metabolism, they do not grow, they produce no waste products, and they do not respond to stimuli. They also don't reproduce independently but must

replicate by invading living cells.

Side note…

2. Viruses are responsible for some of the most dangerous human ailments can be destroyed by altering DNA.

3. Vectors are the agent used to carry new DNA into a cell. ◦ Viruses or plasmids are

often used as vectors

Viruses

Vector Examples a. Tobacco Mosaic Virus (TMV)-

◦ often used as a vector for genetic engineering in plants- 1 long RNA molecule.

b. Bacteriophage- ◦ DNA packaged tightly in a protein head- often

used in genetic engineering. c. Misc. Common Viruses-

◦ Human Immunodeficiency Virus (HIV), Influenza, Common Cold, Measles, Norwalk, Hepatitis, & Rabies.

Vector Examples

Tobacco Mosaic Virus (TMV)-◦ TMV was the first virus to be discovered over a

century ago. Research on TMV has also led to major Nobel prize winning discoveries on general principles of life.

Vector Examples

Bacteriophage

1. Definition- single celled organisms that have no membrane bound organelles and no distinct nucleus. Usually have very short life spans.◦ a. Contain free-floating DNA.◦ b. Can be autotrophic (produce their own energy)

or heterotrophic (consume other things for energy).

◦ c. Also reproduce quickly and mutate often, but are not as tough as viruses Bacteria are the most common examples

Prokaryotic Organisms

2. Other Examples include anything in the Kingdom Monera:◦ a. BACTERIA◦ b. Cyanobacteria◦ c. Blue- Green Algae

Prokaryotic Organisms

Bacteria◦ a. Can be beneficial or harmful to humans.◦ b. Unlike viruses, bacteria are not PARASITES, and

do not need a host.◦ c. MOLDS & FUNGI INCLUDING YEAST ARE NOT

BACTERIA

Bacteria

Escherichia coli

Microbiology in Agriscience and

Production Agriculture11.02: Outline the role of bacteria in agriculture

and the importance of microorganisms in agricultural biotechnology.

A. Beneficial Bacteria (PROBIOTICS)◦ 1. Provide a benefit to human activity through

normal function or manipulation through biotechnology techniques.

◦ 2. Examples: a. 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).

b. Lactobaccillius sp.- a genus of microorganisms that have been introduced to foods (often dairy products) to aid in digestion

Bacteria

1. Pharming- inclusion of cholesterol consuming bacteria in milk products to lower human cholesterol.

2. Bioremediation- use of bacteria that consume contaminants in soil and water. ◦ Ex: bacteria used to “eat” oil from tanker spills, or

excess organic nutrients from animal waste 3. Biocontrol- use of beneficial bacteria in

horticulture to kill harmful bacteria in soil, water, and on plant surfaces.

4. Very few applications in renewable energy or biofuels, but LOTS OF POTENTIAL APPLICATIONS.

Use of Bacteria in Agriscience

1. Affect agriscience products or processes in a negative manner, affecting both plants and animals.

2. Examples:◦ a. Eescherichia coli (E.coli), ◦ B. Clostridium boutlinum (C.boutlinum), ◦ C. Salmonella enteriditus (S.enteriditus), ◦ D. Pythium spp.

3. Methods of destruction / treatment◦ a. Sterilization- kills all living organisms in or on a

substance.◦ b. Pasteurization- kills most harmful microorganisms,

leaving some beneficial organisms surviving.

Harmful Bacteria

1. Can be either beneficial or harmful to plants under different circumstances and conditions.

Examples:◦ a. 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). i) Used in genetic engineering to transmit genes.

Multiform Bacteria

Microbiology in Agriscience and

Production Agriculture11.03: Discuss the structure and function of eukaryotic cells and the role of these cells in

the formation of life.

1. Definition- advanced cells characterized by the presence of membrane bound organelles, and a distinct nucleus.◦ a. Usually occur in multicellular animals, but also

include a few single celled Protists.

Eukaryotic Cells

Structures of ALL cells◦ Cell membrane◦ Golgi apparatus◦ Mitochondria◦ Nucleus◦ Ribosomes◦ Vacuoles

Eukaryotic Cell Structures

a. Cell membrane- ◦ selectively permeable membrane surrounding all

eukaryotic cells. ◦ Protects the cell and controls the movement of

substances into and out of the cell.

Eukaryotic Cell Structures

b. Golgi apparatus- ◦ center for the distribution of proteins, enzymes,

and other materials through the cell. (like the post office)

Eukaryotic Cell Structures

c. Mitochondria- ◦ structures inside the cell that convert simple

sugars to a useful form of cellular energy through the process of respiration.

Eukaryotic Cell Structures

d. Nucleus- ◦ a large central segment of eukaryotic cells that

contains the cell’s genetic information (DNA).

Eukaryotic Cell Structures

e. Ribosomes- ◦ small structures in the cytoplasm of the cell that

utilize RNA to produce proteins for cell functions.

Eukaryotic Cell Structures

f. Vacuoles- ◦ specialized “bubbles” in cells used for storage,

digestion, and excretion. Much larger in plant cells.

Eukaryotic Cell Structures

a. Chloroplasts- ◦ specialized structures in plant cells that utilize

chlorophyll to capture light energy for conversion to chemical energy.

b. Cell wall- ◦ structure outside the cell membrane that helps

support and protect cells. Not semi-permeable.

Structures Specific to Plant Cells

Diploid cells Haploid cells Stem cells

Specialized Eukaryotic Cells

1. Diploid cells- ◦ includes all single celled eukaryotes and every

nonreproductive cell in multicellular eukaryotes. (plants and animals) a. Ex: skin cells, muscle cells, nerve cells, etc.

Specialized Eukaryotic Cells

2. Haploid cells- specialized reproductive cells in Eukaryotes that contain ½ the amount of genetic material of normal (diploid) cells.◦ a. Also called Gametes or sex cells.◦ b. Haploid cells combine during sexual

reproduction to create a fertilized egg.◦ c. 4 distinct types:

i) male- sperm or pollen ii) female- egg or ovum

Specialized Eukaryotic Cells

3. Stem cells- ◦ produced from the union of haploid cells, special

cells that differentiate into all diploid cells in the body.

◦ These cells can differentiate into any diploid cell or remain the same (undifferentiated)

Specialized Eukaryotic Cells

Microbiology in Agriscience and

Production Agriculture11.04: Apply laboratory skills in the

culturing of microorganisms and cells.

1. Most bacteria prefer warm moist environment, though different species require different culturing conditions.◦ a. Bacteria thrive in the harshest environments on

earth- ex: deep sea ocean vents with no sunlight and little useable oxygen.

Ideal Bacteria

1. Bacteria Testing Methods◦ a. Swabbing- method used to test surfaces for

bacteria. i) A sterile cotton swab is dipped in a dilution solution

and rubbed across the surface to be tested. ii) The end of the swab is cut and dropped into the

solution. iii) The infested solution is swirled and .1 ml extracted

for plating.◦ b. Simple Dilution- used to test food and liquids for

the presence of bacteria. Sample should be liquefied and diluted to various concentrations before being plated.

Techniques for Culturing Bacteria

Techniques for Culturing Bacteria

2. Plating- the process of physically spreading bacteria on an agar based culture media.◦ a. To produce agar plates, heat a clear solution in a

water bath. Next, proceed to pour the solution into Petri dishes and immediately seal. (Agar must be heated to be liquefied so that it can be poured.)

◦ b. Bacteria can be spread using an inoculating loop or glass “hockey stick”. i) The slow movement of a cotton swab or inoculating

loop is done to introduce bacteria to a culture plate.◦ c. Plates should be sealed and incubated at 30°C to

avoid the growth of most bacteria harmful to humans. (35°C – 37°C for Salmonella, etc.)

Techniques for Culturing Bacteria

1. Different agar mixes can be used to culture specific types of bacteria.

2. Gram staining is used to broadly identify certain types of bacteria.

3. Identifying individual strains is much more difficult.

Identifying-Counting Bacteria

1. Cultures should be placed in a biohazard bag for sterilization in an autoclave set at 121° C and 15psi for 15 minutes.

2. Agar should be disposed of according to lab protocol- not poured down sinks, as liquid agar can quickly solidify and clog drains

3. 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.

Cleanup after Culture Labs