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Microbiology/Tortora Ch. 6

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Psychrotrophs
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Spoilage microorganisms
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Hyperthermophiles
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Extreme thermophiles, most live in hot springs associated w/ volcanic activity
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Acidophiles
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Tolerate acidity
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plasmolysis
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Shrinkage of cell’s cytoplasm
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Extreme halophiles
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Tolerate/ require high concentrations of salt
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Obligate halophiles
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Require salt
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Falcultative
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Able to grow in salt concentrations up to 2%
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Nitrogen fixatin
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bacteria that use gaseous nitrogen directly from the atmosphere
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Obligate aerobes
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Organisms that require oxygen to live
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Facultative anaerobes
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Aerobic bacteria that can continue to grow without oxygen
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Obligate anaerobes
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Can’t use oxygen for energy
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Singlet oxygen
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Normal molecular oxygen boosted to higher energy state & is extremely reactive
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Superoxide radicals (or superoxide anions)
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Formed during respiration as a final electron acceptor
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Superoxide dismutase
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Enzyme produced by organisms attempting to grow in atmospheric oxygen
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Peroxide anion
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Peroxide produced when superoxide radical converts into molecular oxygen and hydrogen peroxide
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Catalase
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Occurs when peroxide is added to a colony of bacteria (oxygen bubbles released)
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Peroxidase
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Differs from catalase in that its reaction does not produce oxygen
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Hydroxyl Radical
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Intermediate form of oxygen & probably the most reactive
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Aerotolerent Anaerobes
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Cannot use oxygen for growth, but tolerates it fairly well
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Microaerophiles
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Do not require oxygen
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Organic Growth Factors
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Essential organic compunds that an organism is unable to synthesize
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Biofilm
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Slime
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Culture Medium
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Nutrient material prepared for growth of microorganisms in a lab
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Inoculum
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Microbes introduced to culture medium to initiate growth
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Culture
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Microbes that grow & multiply in or on a culture medium
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Sterile
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Contains no living microorganisms
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Agar
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Complex polysaccharide derived from a marine alga
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Chemical Defined Medium
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One whose exact chemical composition is known
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Complex Media
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Made up of nutrients including extracts from yeasts, meat,or plants or digests of proteins from these & other sources
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Nutrient Broth
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Complex medium in liquid form
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Reducing Media
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contain ingrediants that chemically combine with dissolved oxygen & deplete oxygen in the culture medium
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Capnophiles
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Microbes that grow better @ high CO2 concentrations
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Selective Media
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Encourage growth of desired microbes
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Differential Media
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Make it easier to distinguish colonies of desired organism from other colonies growing on the same plate
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Enrichment Culture
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Usually a liquid & it provides nutrients & environmental conditions that favor growth of particular microbe, but not others
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Colony
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Arises from single spore or cell & form clumps or chains
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Streak Plate Method
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Loop dipped in culture & streaked in pattern over surface of nutrient meduim
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Deep Freezing
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Microbes placed in suspending liquid & quick frozen at -50 to -90 degrees C
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Lyphilization
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Freeze-drying, quickly frozen & water removed
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Binary Fission
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Increase in numbers, not size
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Budding
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Grows a bud, enlarges to nearly size of parent cell, then separates
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Generation Time
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Time required for cell to divide & population to double
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Bacterial Growth Curve
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Shows growth of cells over time
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Lag Phase
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No cell division
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Log Phase
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(aka exponential growth phase) Most active period
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Stationary Phase
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period of equilibrium
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Death Phase
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(aka log decline phase) # of deaths exceed # of new cells formed
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Plate Count
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Method of measuring bacterial populations
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Colony-Forming Units
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What plate counts are reported as
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Serial Dilution
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Original inoculum is diluted several times
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Spread Plate Method
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0.1ml inoculum added to surgace of prepared algar, inoculum is spread with a sterilized rod
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Filtration
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Technique to count bacteria
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Most Probable Number Method
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Statistical estimating technique based on the fact that the greater the # of bacterial in a sample, the more dilution is needed to produce density to point @ which no bacteria are left to grow in tubes in a dilution series
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Direct Microscopic Count
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measures bacterial suspension in defined area
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Turbidity
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Monitoring growth, bacteria multiply in liquid and make it cloudy (or “turbid”)
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Psychrophiles
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Cold-loving