Post on 27-Mar-2015
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.