Term
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Definition
- Increase in number of cells, not cell size
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Term
| Physical Requirements for Growth |
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Definition
- Temperature
- pH
- Osmotic pressure
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Term
| Chemical requirements for growth |
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Definition
- carbon
- nitrogen, sulfur, and phosphorus
- trace elements
- Oxygen
- Organic growth factor
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Term
|
Definition
- minimum growth temperature
- optimum growth temperature
- maximum growth temperature
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Term
|
Definition
- Grow between 0o C and 20-30o C
- cause food spoilage
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Term
|
Definition
- Most bacteria grow between pH 6.5 and 7.5
- Molds and yeasts grow between pH 5 and 6
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Term
|
Definition
- grow in acidic environments
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Term
|
Definition
- hypertonic environments, or an increase in salt or sugar, cause plasmolysis
- Extreme or obligate halophiles require high osmotic pressure
- Facultative halophiles tolerate high osmotic pressure
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Term
|
Definition
- structural organic molecules, energy source
- chemoheterotrophs use organic carbon sources
- autotrophs use CO2
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Term
|
Definition
- in amino acids and proteins
- most bacteria decompose proteins
- some bacteria use NH4+ or NO3-
- a few bacteria use N2 in nitrogen fixation
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Term
|
Definition
- in amino acids, thiamine, and biotin
- most bacteria decompose proteins
- some bacteria use SO42- or H2S
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Term
|
Definition
- in DNA, RNA, ATP, and membranes
- a source of phosphours is PO43-
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Term
| Trace element requirements |
|
Definition
- inorganic elements required in small amounts
- usually as enzyme cofactors
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Term
|
Definition
- Singlet Oxygen: 1O2- boosted to a higher-energy state
- Superoxide free radicals: O2-
- Peroxid anion: O22-
- Hydroxyl radical (OH)
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Term
|
Definition
- Organic compounds obtained from the environment
- Vitamins, amino acids, purines, and pyrimidines
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Term
| Characteristics of Biofilms |
|
Definition
- Microbial communities
- Form slime or hydrogels
- Bacteria attracted by chemicals via quorum sensing
- Share nutrients
- Sheltered from harmful factors
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Term
| Medical cases involving biofilms |
|
Definition
- Patients with indwelling catheters received contaminated heparin
- Bacterial numbers in contaminated heparin were too low to cause infection
- 84-421 days after exposure, patients developed infections
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Term
|
Definition
- Nutrients prepared for microbial growth
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Term
|
Definition
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Term
|
Definition
- Introduction of microbes into medium
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Term
|
Definition
- Microbes growing in/on culture medium
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Term
|
Definition
- Complex polysaccharide
- Used as solidigying agent for culture media in Petri plates, slants, and deeps
- Generally not metabolized by microbes
- Liquefies at 100o C
- Solidifies at 40o C
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Term
|
Definition
- exact chemical composition is known
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Term
|
Definition
- Extracts and digests of yeasts, meat, or plants
- Nutrient broth
- Nutrient agar
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Term
|
Definition
- Contain chemicals (thioglycolate or oxyrase) that combine O2
- Heated to drive off O2
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Term
|
Definition
- Microbes that require high CO2 conditions
- CO2 packet
- Candle jar
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Term
|
Definition
- BSL-1: no special precautions
- BSL-2: lab coat, gloves, eye protection
- BSL-3: biosafety cabinets to prevent airborne transmission
- BSL-4: sealed, negative pressure
- Exhaust air is filtered twice
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Term
|
Definition
- Make it easy to distinguish colonies of different microbes
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Term
|
Definition
- Suppress unwanted microbes and encourage desired microbes
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Term
|
Definition
- Encourages growth of desired microbe
- Assume a soil sample contains a few phenol-degrading bacteria and thousands of other bacteria
- Inoculate phenol-containing culture medium with the soil, and incubate
- Transfer 1 ml to another flask of the phenol medium, and incubate
- Transfer 1 ml to another flask of the phenol medium, and incubate
- Only phenol-metabolizing bacteria will be growing
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Term
|
Definition
- A culture containing only one species or strain
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Term
|
Definition
- A population of cells arising from a single cell or spore or from a group of attached cells
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Term
|
Definition
- Also called CFU
- Another name for a colony of bacteria
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Term
|
Definition
- A method used to isolate pure cultures
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Term
| Preserving Bacterial Cultures |
|
Definition
- Deep-freezing: -50o to -95o C
- Lyophilization (freeze-drying): frozen (-54o to -72o C) and dehydrated in a vacuum.
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Term
| Reproduction in Prokaryotes |
|
Definition
- Binary Fission
- Budding
- Conidiospores (actinomycetes)
- Fragmentation of filaments
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Term
| Binary fission in bacteria |
|
Definition
- Cell elongates and DNA is replicated
- Cell wall and plasma membrane begin to constrict
- Cross-wall forms, completely seperating the two DNA copies
- Cells seperate
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Term
| Phases of Bacterial Growth Curve |
|
Definition
- Lag Phase
- Log Phase
- Stationary Phase
- Death Phase
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Term
|
Definition
- First phase in bacterial growth
- Intense activity preparing for population growth, but no increase in population
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Term
|
Definition
- Second phase in bacterial growth
- Logarithmic, or exponential, increase in population.
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Term
|
Definition
- Third stage of bacterial growth
- Period of equilibrium; microbial deaths balance production of new cells
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Term
|
Definition
- Fourth and final stage in bacterial growth
- Population is decreasing at a logarithmic rate
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Term
|
Definition
- After incubation, count colonies on plates that have 25-250 colonies
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Term
|
Definition
- Multiple tube MPN test
- Count positive tubes
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Term
| Direct Methods of Measuring Microbial Growth |
|
Definition
- Plate counts
- Filtration
- MPN
- Direct microscopic count
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Term
| Indirect Methods of Measuring Microbial Growth |
|
Definition
- Turbidity
- Metabolic activity
- Dry weight
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