Chapter 6 Flashcards
Microbial growth
Orderly and permanent increase of the mass of an individual or a population of microbes.
Reproduction
Is an increase in the numbers of individuals and can be independent of growth, although the result of reproduction is usually growth.
Growth Requirements
Nutrients, - carbon, oxygen nitrogen and hydrogen
Chemical and energy requirements
Nutrients - sources of carbon, energy and electrons
Chemical and energy requirements 2 - groups of organisms source of carbon
-Autotrophs -heterotrophs
Chemical and energy requirements 2 - groups of organisms
- chemotrophs - phototrophs
Physical requirements temperature
Effect of temperature on proteins - very high temp can cause denaturing Effect of temperature on membrane of cells and organelles -if too low, membranes become rigid and fragile -if too high, membranes become too fluid
Effects of temperature on bacterial growth
Psychrophiles: “cold lovers” grow at -5C to 20C Mesophiles: “middle-loving”, grow at 15C-45C Thermophiles: “heat-lovers”, grow at 45C-80C
Physical requirements: pH
Neutrophils - normal Range (6.5-7.5) Acidophiles - best grown in acidic habitats Alkalinophiles - live in alkaline soils and water
Acidophiles
Grow best in acidic habitats
Alkalinophiles
Live in alkaline soils and water
Isotonic solution
No bet movement of water
Hypotonic solution
War will move into the cell (cell swells up and can lyse)
Hypertonic solution
Water moves out of the cell (cell shrinks, plasmolysis)
Hydrostatic pressure Barophiles
Live under extreme pressure. Depends on pressure to maintain shape
O2 requirements Obligate Aerobe
O2 is essential
Obligate Anaerobes
O2 is deadly
Radical
Oxydation
Superoxide Radical (SOR)
Extremely toxic to living cells
Superoxide dismutase (SOD)
Enzyme that neutralizes SOR -produced by all organisms in the presence of O2. SOD coverts superoxide radical to hydrogen peroxide (H2O2) which is also toxic
2 enzymes that naturalize Hydrogen Peroxide
Catalase Peroxidase
Catalase
presence of this enzyme in an organism can be detected by applying hydrogen peroxide to a culture (on solid media) and observing presence of bubbles.
Peroxidase
no bubbles reaction doesn’t produce gaseous oxygen, no bubbling and be seen when applying hydrogen peroxide
Obligate Aerobes
require oxygen for growth
Facultative Anaerobes
can grow with or without oxygen (prefers CO2 than oxygen)
Obligate Anaerobes
cannot tolerate molecular oxygen (prefers CO2)
An organism growing at the top of a broth is most likely to be…
Anabolism seases because of…
insufficient nitrogen
Nitrogen is acquired from…
organic and inorganic nutrients
All cells recycle nitrogen from
amino acides and nucleotides
Nitrogen fixation by certain bacteria is…
essential to life on earth
Other Chemical Requirements
Phosporus
Sulfur
Trace elements - small amounts of zinc, manganese, chromium,
Growth Factors - Necessary organic chemicals that cannot be synthesized by certain organisms
Vit/Min are?
Cofactors
Cultures composed of cells arising from a sing progenitor called a
CFU - one species aka pure culture
Aseptic technique prevents contaimination of
sterile substances or objects
2 common isolation techniques
- streak plate
- Pure plates
most microorganisms in nature are found in
mixed cultures
Isolation of colonies is done using what technique
steak plate technique
Which technique prevents contamination of sterile substances or objects
Aseptic Technique
Each isolated colony begins as a single bacterium called:
CFU
Broths is used for what?
rapid growth
Maintenance of cultures are stored in
Slants
a synthetic or complex medium can be solidified using agar
Solid Media
Usually .5% agar, used for motility studies (SIM medium)
Semi-solid media
not agar, but broth; used for propagation of cultures
Liquid Media
nutrient material prepared for the growth of microorganisims in the laboratory ( must initially be sterile)
Culture media
made of known amounts of chemicals
synthetic (or defined) medium
some ingredients are of unknown composition or amount (extracts of plants, yeast or meat). known as?
- Nutrients broth / TSA
- Tryptic soy broth (TSB)
Complex medium
A culture intended to be kept for a long period of time is best kept in a…
Agar Slant
Generial Media
provies basic needs of organisms
encourages the growth of certain organism while discouraging the growth of others:
Selective medium
Selective for Gram -
McConkey
selective and differential medium
Selective for Gram +
Columbia
distinguishes between different groups of bacteria - the media contains constituents which cause an observable change ( color or pH)
Differential Medium
Differential Medium that caintains lactose and neutral red, lactose
MacConkey
Gram negative -
binary fission produces two identical cells, each with one full chromosome
Bacterial division
