Microbiology in Agriscience and Production Agriculture

Competency 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

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 funguses 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 boutlinum– Salmonella enteriditus– 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.