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69 Cards in this Set
- Front
- Back
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psychrophiles
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cold-loving microbes; capable of growing 0 C; optimal growth 15 C; will not grow in temp over 25 C; found mostly in ocean's depth or polar regions
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mesophiles
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moderate temperature-loving microbes; most common spoilage and disease organism; optimal growth 25-40 C;
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psychrotrophs
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cold-loving; growth at 0-40 C optimal growth 20-30 C; grow well at refrigerator temps; most likely assoc with low temp food spoilage
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hyperthermophiles
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optimum growth temp 80 C or higher; found in hot springs assoc with volcanic activity
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thermophiles
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optimum growth 50-60 C; can't grow below 45 C; not considered a public health problem
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minimum growth temperature
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lowest temp at which a species will grow
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optimum growth temperature
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temperature at which the species grows the best
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maximum growth temperature
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highest temperature at which growth is possible
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acidophiles
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grow in high levels of acidity
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plasmolysis
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shrinkage of the cell's cytoplasm
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obligate halophiles
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require at least 30% salt concentrations for growth
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facultative halophiles
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don't require high salt concentrations for growth; able to grow at salt concentrations of 2%
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nitrogen
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used by organisms primarily to form the amino group of the amino acids of proteins
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nitrogen fixation
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the conversion of N2 into ammonia
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symbiosis
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the living together of two different organisms or populations
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trace elements
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small amounts of mineral elements
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oligate aerobes
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organisms that require oxygen to live
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facultative anaerobes
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organisms that can use oxygen when its present but are able to continue growth by using fermentation or anaerobic respiration when oxygen is not available; energy production decreases in the absence of oxygen
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obligate anaerobes
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bacteria that are unable to use molecular oxygen for energy-yielding reactions; harmed by oxygen; genus Clostridium
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aerotolerant anaerobes
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can't use oxygen for growth but tolerate it well; many aerotolerant bacteria ferment carbohydrates to latic acid
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micoaerophiles
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aerobic bacteria; grow only in oxygen concentrations lower than those in air
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organic growth factors
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essential organic compounds an organism is unable to synthesize; must be obtained from the evironment; Ex, vitamins, amino acids, purines
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culture medium
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a nutrient material prepared for the growth of microorganisms in a laboratory
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inoculum
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microbes introduced into a culture medium to initiate growth
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culture
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microbes the grow and multiply in or on a culture medium
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sterile
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containing no microrganisms
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agar
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a complex polysaccharide dervived from a marine alga
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nutrient broth
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complex medium in liquid form
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nutrient agar
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complex medium in liquid form with the addtion of agar
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capnophiles
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microbes that grow better in high concentrations of carbon dioxide
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colony
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a visible mass of microbial cells arising from one cell or form a group of the same microbes
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streak plate method
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most common isolation method used to get a pure culture
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deep-freezing
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a process in which a pure culture of microbes is placed in a suspending liquid and quick-frozen at temps ranging from -50 to -95 C
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lyophilization (freeze-drying)
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a suspension of microbes is quickly frozen at temp ranging from -54 to -72 C and water is removed by a vacuum
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budding
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form a small initial outgrowth that enlarges until its size approaches a parent cell and then separates
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generation time
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time required for a cell to divide; varies with different organisms
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bacterial growth curve
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shows growth of cell over time
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lag phase
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period of little or no cell division; can last for 1 hour or several days; cells are dormant
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log phase/exponential growth phase
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second phase of growth when cell begins to divide and enter a period of growth; cellular reproduction is most active; microbes sensitive to adverse conditions
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stationary phase
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growth rates slow down; number of microbial deaths balances number of new cells; metabolic activities in surviving cells slow; period of equilibrium
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death phase/logarithmic decline phase
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number of deaths exceeds the number of new cells; phase continues until population is diminished to a tiny fraction of the number of cells in the stationary phase or dies out
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plate count
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most frequently used method of measuring baterial populations; measures the number of viable cells; take time
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serial dilution
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dilution of the original inoculum; done to prevent inaccurate counts of colonies
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colony-forming units (CFU)
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how plate counts are reported
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chemically defined media
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one whose exact chemical composition is known; growth of chemoautotrophs & photoautotrophs
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complex media
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chemical composition varies from batch to batch; includes extracts from yeasts, meat, or plants, or digests of proteins from these and other sources; growth of most chemoheterotrophic organisms;
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selective media
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designed to suppress the growth of unwanted bacteria and encourage the growth of the desired microbe
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differential media
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designed to distinguish between colonies of the desired organism from other colonies growing on the same plate
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enrichment culture
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usually liquid and provides nutrients and evironmental conditions that favor the growth of a particular microbe but not others; designed to increase numbers of a desired microbe to detectable levels
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reducing media
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designed for the cultivation of obligate anaerobes
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fastidious organisms
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organisms that require many growth factors
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chemoheterotrophs
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an organism that uses organic molecules as a source of carbon and energy
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chemoautotrophs
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an organism that uses inorganic chemical as an energy source and CO2 as a carbon source
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heterotrophs
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an organism that requires an organic carbon source
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autotrophs
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an organism that uses carbon dioxide as its principle carbon source
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MacConkey Agar
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differential/selective media; selects for gram - & lactose fermenting bacteria; positive red, clear non fermenters
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Esoin-Methylene Blue Agar
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differential/selective media; selects for gram - & differentiate between members of the Enterbacteriaciae family; E. coli produce metallic green, Enterbacter genus grow pink
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Indole
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measures production on indole from the amino acid trytophan; positive red, negative yellow
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Methyl Red
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measures oxidation of glucose to acidic products; positive red, negative yellow
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Vogues-Proskauer
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measures production of acetoin and ethanol from glucose; positive pink/red, negative yellow
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Triple Sugar Iron
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measures ability of bacteria to ferment sugars to produce hydogen sulfide; yellow indicates ability to ferment sugars into acidic by products, red/pink indicates dextrose (glucose) only sugar fermented, black indicates reduction of sulfur into hydrogen sulfide
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Alpha hemolysis
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incomplete lysis of red blood cells; greenish in color
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Beta hemolysis
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complete clearing of the area around any colonies; complete lysis
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Gamma hemolysis
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no lysis of red blood cells
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TSA
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Complex media, grows most bacteria, normal no changes
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Blood Agar
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Enriched/Differential media; grows most bacteria; detects hemolytic bacteria
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Phenyl Ethyl Alcohol Agar
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Selective media; gram +; normal no change
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Mannitol Salt Agar
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selective/differential media; gram +; S. aureus yellow, S. epi red
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Simmons Citrate
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measures the ability of a bacterium to ferment citrate as its sole carbon source into sodium bicarbonate; positive blue, negative green
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