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Definition
- Study of microorganisms (or microbes)
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Term
Microorganisms (or Microbes) |
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Definition
- Organisms and agents too small to be clearly seen by the unaided eye.
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Include bacteria, archaea, protozoa, algae, fungi and viruses.
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| Microorganisms relationship to humans |
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Definition
Pathogens: Disease-causing microbes e.g. Streptococcus - “Strep Throat” Influenza virus - “Flu” Normal flora: Microbes found in/on healthy individuals e.g. E. coli – in intestine Staphylococcus – on skin |
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Term
| Bacteria that belongs to group legumes |
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Definition
A bacteria that belongs to the group legumes is the only one that can convert essential nitrogen that can be used by animals and plants. Animals and plants cannot convert N2 to a useable form of nitrogen without bacteria |
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- First person to publish the depiction of a microorganism
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Described the fruiting structure of molds in 1665 (~20 years before Leeuwenhoek)
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Definition
- Life arises spontaneously from non-living matter
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Aristotle (384-322 B.C.) thought some simpler invertebrates could arise from spontaneous generation
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Definition
- Life arises from pre-existing life
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Definition
- Biogenesis of large organisms was proven by francesco Redi
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Meat were placed in (1) open jars, (2) jars covered with paper, and (3) jars covered with gauze. -
(1) Maggots were produced on meat in the open jars. (2) Maggots were not produced in the paper-covered jars. (3) Eggs and maggots were visible in the gauze, but not on meat. - Concludes that
maggots were formed on meat only when flies were present, because flies carried eggs of maggots.
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Definition
- Proved biogenesis of microorganisms with swan neck flasks
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| Disease is caused by microorganisms (germs) |
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Definition
- Demonstarted the relationship between bacteria and diseases.
- Established relationship between Bacillus anthracis and anthrax
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Scientific method to prove causation of disease Developed pure culture methods: - growth (of bacteria) on solid media - isolation of pure cultures
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Term
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Definition
1. The suspected pathogenic organism should be present in all cases of the disease and absent from healthy animals 2. The suspected organism should be grown in pure culture Only one type of organism should be present 3. Inject pure culture à healthy host animal Experimental animals develop same signs and symptoms as original diseased animal 4. The organism should be re-isolated and shown to be the same as the original |
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Definition
Cells are physically separated from each other and from the outside environment by a cell membrane and in some cases a cell wall |
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| Basic properties of cells |
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Definition
- Metabolism
- Reproduction
- Differentiation
- Communication
- Movement
- Evolution
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Characteristics: Single cells Lack nucleus 70 S Ribosomes Size: 1-10 mm |
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Characteristics: Simple shapes: round, rod, spiral Cell walls: peptidoglycan |
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Definition
Characteristics: Cell wall: more complex than bacteria (emphasis) Found in extreme environments: - High temperature (above boiling point) - High pressure (in deep ocean) - High salt (in salt lake) Archaea are so different from bacteria that they have been re-classified as a separate domain a few years ago. Archaea can do photosynthesis without sunlight |
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Term
Streptomyces thermoautotrophicus |
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Definition
N2 fixation Found in burning charcoal piles |
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Definition
Characteristics: Single-celled or multi- cellular Have a true nucleus 80 S Ribosomes Size: 10 – 100 mm |
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Definition
Characteristics: Single-celled No cell walls Motile Aquatic environments Part of food chain Some are pathogens |
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Characteristics: Single-celled or multicellular Have cell walls Photosynthetic In soil, oceans, lakes Some produce toxins |
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Characteristics: Single-celled or multicellular Have cell walls No photosynthetic pigments Nature’s “recyclers” (can detoxify a lot of toxins) Some are pathogens |
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Acellular Microorganisms: Viruses |
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Definition
Characteristics: A Major class of microorganism Not cellular Made of nucleic acid + protein Obligate intracellular parasites (cannot live by themselves, must depend on a host) |
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Definition
- used rRNA sequencing to compare organisms and led to the discovery of Archae
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Term
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Definition
- 1-10um
- Nanobacteria less than 0.2um
- E coli 2um
- Epulopiscium fishelsoni size of hypen
- Thimargarita namibiensis
head of fruit fly 750um
- Smallest bacteria about the size of largest virus
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Term
Show prokaryotic cell shape of - coccus
- bacillus
- spirillum
- spirochete
- stalk
- hypha
- filamentous
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Definition
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Term
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Definition
Contains cytoplasmic material that is devoid of ribosomes and DNA. Function maybe in nutrient absorption. If you allow Caulobacter crescentus to grab onto the tip of a pipette and suck the budding area, you can lift the pipette tip up. |
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Definition
e.g. streptomyces (fungus like bacteria) Supports & protects the cells. |
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| Spherical bacteria shapes cocci |
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Definition
•Diplo – pairs Staphylo – grape-like clusters Strepto – chain |
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Definition
•Vibrios - curved rods • •Spirilla - 2 or more twists • •Spirochetes - corkscrew shaped • |
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•Monomorphic •Pleomorphic |
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Definition
•Monomorphic - single shape •Pleomorphic - variable shape |
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Term
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Definition
Composed of: - Phospholipid bilayer (Phospolipids are structurally asymmetric polar & nonpolar end)
- Membrane proteins (integral & peripheral protein)
- •Phospholipids - form bilayer
- •Hopanoids - embedded in bilayer –Sterol-like (similar to cholesterol) –Stabilize membrane
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Term
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Definition
Functions: •Nutrient uptake & Waste excretion e.g. glucose uptake •Metabolic processes e.g. photosynthesis, respiration •Signal transduction e.g. chemotaxis Composed of: - •Integral proteins embedded in membrane –amphipathic proteins
– - •Peripheral proteins –loosely attached
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Term
| Plasma membrane functions |
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Definition
•separation of cell from its environment •selectively permeable barrier – •location of crucial metabolic processes –respiration, photosynthesis, synthesis of lipids and cell wall constituents •detection of and response to chemicals in surroundings with the aid of special receptor molecules in the membrane |
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Definition
Internal membrane system (pinched off plasma membrane) Mesosomes: •may be invaginations of the plasma membrane possible roles: cell wall formation during cell division chromosome replication and distribution secretory processes •may be artifacts of chemical fixation process |
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Definition
•Substance between membrane and nucleoid • •Primarily water (70%) • •Thick and elastic • •Packed with inclusion bodies and ribosomes • •Highly organized with respect to protein location |
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Definition
•Structure: made of organic or inorganic materials •Function: nutrient & energy storage; others •Examples: –poly-b-hydroxybutyrate: phosphate storage and biodegradable plastics –gas vacuoles: provide buoyancy –magnetosome: iron containing, orientation in magnetic field, used to located oxygen concentration •Note: may be visible in light microscope; used for identification purposes • |
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Definition
•Extra-chromosomal DNA •Small, circular “mini-chromosomes” •Function: Extra genetic information –Not required for cell growth –May provide selective advantage (antibiotic resistance) •Plasmids can be transferred between bacteria via conjugation • |
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Definition
•Provides characteristic shape to cell •Protects the cell from osmotic lysis •May also protect cell from toxic substances •Composed of peptidoglycan |
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Definition
Enormous polymer composed of many identical subunits Glycan - sugars N-acetyl-glucosamine (NAG) N-acetyl-muramic acid (NAM) Basic unit of peptidoglycan is formed by NAG and NAM Alternating NAG/NAM form sugar chians The cross-bridge between NAM’s tails link sugar chains together. |
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Term
Cell wall of bacteria divided into Gram + |
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Definition
•Gram Positive (G+) –Thick layer of peptidoglycan –No outer lipid layer –Stain purple in Gram stain Has Peptide interbridge • •Contains teichoic acid - Antigen in G+ - Provide negative charge - Composed of : glycerol, phosphate, amino acids or Sugar •Lacks LPS (lipopolysaccharide) •Antibiotic susceptibility: –Penicillin sensitive Flagella basal body composed of 2 rings |
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Cell wall of bacteria divided into Gram - |
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Definition
•Gram Negative (G-) –Thin layer of peptidoglycan –Has outer lipid layer –Stain red in Gram stain •More complex than G+ cell wall •Has thin layer of peptidoglycan •Lacks teichoic acid •Contains LPS (lipopolysaccharide) - Antigen in G- - Provide negative charge •Antibiotic susceptibility: –Penicillin resistance • •Outer membrane is a barrier to transport •Provide protection against: –antibiotics –digestive enzymes •Is more permeable than plasma membrane due to porin proteins (e.g. let glucose through) Thicker periplasmic space Flagella basal body composed of 4 rings |
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Definition
•Contains: -Lipid A -Core polysaccharide -O-side chain •LPS functions: -Give overall negative charge to cell surface -Stabilizes membrane structure -Can act as endotoxin - |
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Term
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Definition
•Area between plasma membrane and outer membrane •Functions: peptidoglycan synthesis, nutrient acquisition & modification of toxic compounds (e.g. hydrolytic enzymes) |
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Definition
Prokaryotic structure •Short, hair-like structures •Only found in G- •Used for attachment (adhesion protein) à invasion, nutrient uptake •Not used for motility •Pili –Special type of fimbrae –May be used for DNA transfer |
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Term
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Definition
Monotrichous
One polar flagellum
Amphitrichous
One flagellum at each pole
Peritrichous
Flagella spread evenly over the whole surface
Lophotrichous
Cluster of flagella at one or both ends
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Term
| Bacteria movement via flagella |
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Definition
•“Runs” –swims smoothly along –counter-clockwise rotation of flagella •“Tumbles” –cell stops and tumbles by reversing the direction of flagella rotation –clockwise rotation of flagella |
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Definition
•Definition: - A “resting or dormant state” structure within bacterial cell. •Function: –Survival of adverse conditions –Can be “re-activated” in favorable environment (e.g. nutrient-rich environment) – •Two reverse processes: Sporulation = spore is formation under stress (starvation, heat, radiation, chemicals, desiccation) Germination = spore is transformed into a vegetative cell • •Example organisms that form spores: - Bacillus, Clostridium Position of spores can be used for identification central spore subterminal spore terminal spore |
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Definition
•(Re)activation –prepares spores for germination –often results from treatments like heating •Germination –spore swelling –rupture of absorption of spore coat –loss of resistance –increased metabolic activity •Outgrowth –emergence of vegetative cell |
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Term
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Definition
•Psychrophiles = cold-loving –Growth at 0-20 oC –Optimum: 15 oC or less –Found in polar habitats •Enzymes, transport systems and protein synthesis work well at low temperatures – •Membranes contain high levels of unsa-turated fatty acids and remain semifluid |
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Definition
•Psychrotrophs = facultative psychrophiles –Can grow at 0-7 oC –Optimum: 20-30 oC –Food spoilage organisms |
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Thermophiles What are the adaptations? |
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Definition
•Thermophiles = heat-loving –Prefer 55-65 oC or higher –Found in hot water lines, compost piles Adaptations of thermophiles •Protein structure stabilized by a variety of means –e.g., more hydrogen bonds –e.g., more prolines –e.g., chaperones – •DNA stabilized by histone-like proteins • •Membrane stabilized by a variety of means –e.g., more saturated, more branched and higher molecular weight lipids –e.g., ether linkages (archaeal membranes) |
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Definition
•Hyperthermophiles = more heat-loving –Prefer 80-100 oC (or higher è140oC!) –Found in geothermal areas of ocean floor |
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Definition
•Mesophiles = like moderate temperatures –Prefer 20-45 oC –Includes most human pathogens |
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Definition
•Neutrophiles (most bacteria) - Prefer neutral pHs (between pH 5.5-8.0) |
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Definition
•Acidophiles –Prefer acidic pHs (less than pH 5.5) |
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Definition
•Alkalophiles –Prefer alkaline pHs (greater than 8.5) |
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Adaptation of Acidophiles & Alkalophiles |
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Definition
•most acidophiles and alkalophiles maintain an internal pH near neutrality –some use proton (H+)/ion exchange mechanisms to do so •some synthesize proteins that provide protection –e.g., acid-shock proteins (chaperones) •many microorganisms change pH of their habitat by producing acidic or basic waste products –most media contain buffers to prevent growth inhibition |
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Osmotolerant organisms Adaptations |
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Definition
•Can tolerate high [solute] outside cell •Solute = sugar, salt •e.g. Staphylococcus aureus (halotolerant) - found on human skin - can grow up to 3 M salt èMany use compatible solutes to increase their internal osmotic concentration èSynthesis or uptake of solutes that are compatible with metabolism and growth (e.g. amino acids) |
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Obligate aerobe Facultative anaerobe Microaerophile Aerotolerant anaerobe Obligate anaerobe |
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Definition
Obligate aerobe requires oxygen; cannot live without oxygen Facultative anaerobe lives with or without oxygen; prefers oxygen Microaerophile requires oxygen in reduced concentration O2 concentration = 2-10% Aerotolerant anaerobe does not require oxygen but, is not harmed by oxygen Obligate anaerobe cannot use and detoxify oxygen and, is killed by oxygen (i.e. oxygen is toxic) • |
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Term
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Definition
Oxygen in the cell is readily reduced by electrons, resulting in the formation of toxic (and extremely reactive) products, such as superoxide radicals and hydrogen peroxide, which damage macromolecules in cells. Superoxide radical O2 + e- è O2-• Hydrogen peroxide O2-• + e- + 2 H+ è H2O2 |
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Definition
•Superoxide dismutase (SOD) –Removes superoxide radicals –Reaction: 2 O2-• + 2 H+ à H2O2 + O2 – •Catalase and Peroxidase –Removes hydrogen peroxide –Catalase reaction: 2 H2O2 à 2 H2O + O2 –Peroxidase reaction: H2O2 + 2 H+ à 2 H2O |
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–required in relatively large amounts – –over 95% of microbial cell dry weight is composed of these elements C, O, H, N, S, P components of carbohydrates, lipids, proteins, and nucleic acids Heterotroph Carbon derived from living organisms Autotrophs Carbon derived from nonliving organisms oxygen and hydrogen obtains from organic compounds or water K, Ca, Mg, Fe (cations) K: required for activity of enzymes, some involved in protein synthesis Ca: contributes to the heat resistance of endospores Mg: serves as cofactor for many enzymes, stabilizes ribosomes and cell membranes Fe: part of the cytochromes, a cofactor for enzymes and electron-carrying proteins |
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Definition
•Trace elements (micronutrients) • –Mn, Zn, Co, Mo, Ni, Cu – –required in trace (very small) amounts – –ubiquitous à can be obtained from water, glassware and regular medium for growth – –important for cell growth despite low concentration |
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Definition
•Organic Growth Factors - organic compounds - essential cell components (or their pre- cursors) that the cell cannot synthesize because of the lack of synthetic enzymes - must be supplied by environment if cell is to survive and reproduce •Amino acids –needed for protein synthesis – •Purines and Pyrimidines –needed for nucleic acid synthesis – •Vitamins –function as enzyme cofactors –only a small amount is required to sustain growth |
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Definition
• Bacteria are incubated in a closed culture vessel with a single batch of medium where no fresh medium is introduced • Nutrient concentration declines Waste concentration increases |
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Bacteria growth in a closed system Lag phase |
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Definition
Lag phase: - Following transfer to new media - Adjustment period (i.e. old cells, injured cells, different medium) - Very slow growth - Cells eventually re-tool, replicate DNA, increase in size, and finally divide |
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Bacteria growth in a closed system Exponential phase |
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Definition
Exponential phase: - sufficient nutrients & optimal genetic potential - Exponential growth phase - Rapid growth at constant rate - Shortest generation time possible |
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Bacteria growth in a closed system Stationary phase |
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Definition
Stationary phase: -Nutrients are limited -Oxygen is limited (e.g.aerobes) -Accumulation of toxic waste (e.g.Streptococci à lactic acid) -Critical population is reached -Cell growth slows down -#living cells = #dying cells |
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Bacteria growth in a closed system Death phase |
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Definition
Decline (death) phase: - Nutrient depletion & waste accumulation - Irreversible loss of ability to reproduce - Number of living cells declines |
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| Counting chambers as measurement of bacteria growth |
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Definition
“determination of microbial number through direct counting” - easy, inexpensive, and quick -useful for counting both eukaryotes and prokaryotes - cannot distinguish living from dead cells |
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| Plating method measurement of bacteria growth |
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Definition
Plate Samples è Each microorganism develops into one colony |
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| membrane filtration as measurement of bacteria growth |
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Definition
| filter colonies out of water and view bacteria colonies on filter |
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Measurement of Bacterial Growth - Turbidimetric Measurement - |
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Definition
more cells in test tube
more cell mass in test tube
more light scattered
less light detected |
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| Total cell count and variable cell count |
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Definition
•Total Cell Count –turbidity or microscope count –doesn’t distinguish live & dead cells •Viable Cell Count –plate count or membrane filtration –only live (viable) cells grow |
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| Chemically defined media and complex media |
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Definition
Chemically defined media - the precise composition is known Complex media – the precise composition is not known |
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Definition
•peptones –protein hydrolysates prepared by partial digestion of various protein sources •extracts –aqueous extracts, usually of beef or yeast •agar –sulfated polysaccharide used to solidify liquid media |
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Definition
Selective media agents added that inhibit certain microbes e.g. “Brilliant green agar” Dye inhibits G+ bacteria; used to grow G- bacteria selectively |
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Definition
Dye inhibits G+ bacteria; used to grow G- bacteria selectively |
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Definition
Differential media agents added that differentiate between microbes e.g. “Blood agar” Blood cells are lysed only by pathogenic bacteria, such as Streptococcus secretes “hemolysins” (exozyme) |
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Blood cells are lysed only by pathogenic bacteria, such as Streptococcus differential media |
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Definition
(1) Dye - inhibits G+ bacteria; allows growth of G- (2) Lactose - detects lactose fermentation (pink colonies) |
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