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91 Cards in this Set
- Front
- Back
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What is growth?
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an increase in a population of microbes
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What is a colony?
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a pile of bacterium that arose from a single bacterium dividing by binary fission
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Do all microbes need an energy source?
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yes
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What are microbes called if they use light as an energy source?
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phototroph
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What are microbes called if they use an organic compound as an energy source?
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heterotroph
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What are microbes called of they use an inorganic compound as an energy source?
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lithotroph (hydrogen, hydrogen sulfide, nitrate, amonia)
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What are the microbes called if they use CO2 as a carbon source?
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autotroph
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What are microbes called if they use CO2 as a carbon source?
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heterotroph
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What nutritional type of bacteria are human pathogens?
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heterotrophs
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What are the chemical requirements for growth?
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-carbon
-hydrogen -nitrogen -oxygen -trace elements |
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How much of the dry weight of a microbe carbon?
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50%
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Is carbon considered the building block of life?
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yes
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Why do you need carbon?
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need it to produce carbs, proteins, lipids, and nucleic acids
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Where do we usually get the hydrogen we need?
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from water
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How much of the dry weight of a microbe from nitrogen?
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15%
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Why do you need nitrogen?
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need it to produce proteins, ATP, and nucleic acids
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How much oxygen do microbes need?
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different microbes have different oxygen requirements; depends on the type of microbial metabolism microbe is capable of
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What is an obligate aerobe?
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it requires oxygen
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What kind of energy production does an obligate aerobe do?
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-does aerobic energy production (using oxygen at end of ETC)
-or does fermentation |
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Where would the growth be in a test tube with an obligate aerobe?
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only at the very top
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What is an obligate anaerobe?
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it cannot handle oxygen; oxygen is harmful
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What kind of energy production does an obligate anaerobe do?
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-does anaerobic energy production (uses sulfate or nitrate)
-can do fermentation |
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Where would the growth be in a test tube with an obligate anaerobe?
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only at the very bottom
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What is a microaerophile?
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they prefer a lower oxygen concentration; it likes only 2-10% oxygen
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What kind of energy production does a microaerophile do?
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-does aerobic energy production
-or can do fermentation |
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Where would the growth be in a test tube with a microaerophile?
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little space at the very top, then growth towards the top under the space
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What is an aerotolerant anaerobe?
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it is anaerobic energy production that happens in the presence of oxygen
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Does oxygen kill an aerotolerant anaerobe?
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No; it is not inhibited or killed by oxygen, it only tolerates it
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What kind of energy production does an aerotolerant anaerobe do?
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-it does not do aerobic
-does anaerobic energy production (using sulfate or nitrate) -can do fermentation |
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Where is the growth in a test tube with an aerotolerant anaerobe?
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equal growth throughout entire test tube
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What is a facultative anaerobe?
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it does aerobic energy production, anaerobic energy production, and fermentation
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What kind of energy production does a facultative anaerobe do ?
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-aerobic
-anaerobic -ferment |
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Where is the growth in a test tube that has a facultative anaerobe?
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there is more growth at the top of the tube, but a small amount at the bottom
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What trace elements are chemical requirements for growth?
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-iron
-copper -zinc -phosphorus -sulfur |
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Why are the trace elements such as iron, copper, and zinc needed?
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They are cofactors for many enzymes
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Why is the trace element phosphorus needed?
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it is needed to build membranes
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Why is the trace element sulfur needed?
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needed to make proteins
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What are the physical requirements for growth?
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1)temperature
2)pH 3)osmotic pressure |
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What is minimun growth temperature?
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lowest temp where there is growth
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What is optimum growth temperature?
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the best temp for growth
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What is the maximum growth temperature?
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the highest temp where there is growth
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What is a psychrophile?
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a cold loving microbe; food spoilage
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What temperature for psychrophile?
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below 15 degrees C
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Are psychrophiles considered human pathogens?
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no
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What are mesophiles?
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moderate temperature loving microbes; 20-40 degrees C
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Are mesophiles considered human pathogens?
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yes
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What is a thermophile?
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a heat loving microbe; 40-80 degrees C
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Where do you find thermophiles?
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in compost piles
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What is a hyperthermophile?
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extreme heat loving microbes; above 80 degrees C
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Where do you find hyperthermophiles?
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Archae; hot water vents on ocean floor
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To maintain pH in media, what do you add?
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buffers
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What is a neutrophile?
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microbe that grows best in pH of 6.5-7.5
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Which pH microbe is the most common?
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neutrophile
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What is an acidophile?
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microbe that grows best in acidic conditions; less than a pH of 6.5
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What is an alkalinophile?
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microbe that grows best in alkaline conditions; pH above 7.5, but not above 11.5
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What is osmotic pressure?
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the pressure exerted on a semi-permeable by a solution containing solutes that cannot freely cross the semi-permeable membrane
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What are in solutes that affect the osmotic pressure?
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sugar or salt
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Hypertonic solution?
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causes water to osmose out of microbe; the microbe will then shrivel and shrink= death
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Hypotonic solution?
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causes water to osmose into microbe; resulting in the microbe exploding
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What is osmosis?
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water will osmose to a place of high water concentration to a place of low water concentration
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What is culture media?
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nutrient material that is suitable for the growth of microbes
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Is culture media sterile?
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yes
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What is used for culture media?
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-broth (liquid)
-agar (solid) |
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What is defined or synthetic media?
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the exact chemical compostition is known
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Is defined or synthetic media commonly used? Why?
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no, because its expensive
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What is complex media?
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composition that varies batch to batch; contains extracts (meat, protein, yeast)
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What type of media supports growth of a wide variety of microbes?
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complex media
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Is complex media commonly used? Why?
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yes, its inexpensive
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What type of media is most commonly used?
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complex media
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What is selective media?
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it encourages the growth of wanted microbes and inhibits the growth of unwanted microbes; for high salt loving microbes
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What is used for selective media?
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mannitol salt agar (high amount of salt); inhibits growth of most bacteria
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What is differential media?
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makes it easy to distinguish different types of bacteria
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What is used for differential media?
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mannitol salt agar= can you ferment sugar mannitol?; blood agar= differentiate based on the ability to lyse red blood cells
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What if you can ferment the sugar mannitol in a differential media?
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then you can differentiate between Staph aureas and Staph epidermis
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How many ways can you preserve microbes?
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-short term= fridge
-long term=deep freeze (-50 to -95 degrees) for years -very long term (lyophilization) |
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What is lyophilization?
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to remove water under a vacuum; put into a powder (good for decades)
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What is the generation time?
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the time required for bacterium to divide by binary fission
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What is the generation time of E. coli?
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20 minutes
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What is the generation time of most bacteria?
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1-3 hours
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What is the generation time of mycobacterium leprae
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10 days
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What are the phases of the growth curve?
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-lag phase
-log phase -stationary phase -death phase |
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What are the two ways to measure microbial growth?
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-direct methods
-indirect methods |
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What are the direct methods of microbial growth?
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-viable plate count (count # of colonies)
-membrane filtration -microscopic grid count -electric counters |
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What are the indirect methods of microbial growth?
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-turbidity
-metabolic activity= amount of nutrients -dry weight of the broth |
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What is the lag phase?
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1st step in growth curve; bacteria is adjusting to new environment; no increase or decrease in bacteria; can last several hours to several days; needs time to produce enzymes needed to catabolize nutrients available
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What is the log phase?
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2nd step in growth curve; constant binary fission; most active metabolically; most susceptible to damage (chemicals, drugs); signs and symptoms of disease usually begin; huge increase of bacteria
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What is the stationary phase?
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3rd step in growth curve; no increase or decrease in # of bacteria; wastes accumulating; pH is changing; running out of nutrients
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What is the death phase?
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4th step in growth curve; huge decrease in # of bacteria; wastes accumulated; too large of a change in pH; no nutrients available
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In what phase of the growth curve are the bacteria most susceptible to damage?
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log phase
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In what phase of the growth curve do signs and symptoms of disease begin?
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log phase
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In what phase of the growth curve does the pH start to change?
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stationary phase
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